A package containing a suspicious substance caused a full-scale alert at Shipley's sorting office today, as a wave of anthrax scares swept across Britain.

Police, firefighters and paramedics sealed off the building in Otley Road as more than 60 Post Office workers were evacuated at about 6am.

One postal worker, who colleagues said tasted the substance, was interviewed by paramedics before being taken to Bradford Royal Infirmary.

He and five other postal workers were put through a mobile decontamination unit set up by firefighters before being taken to hospital where they waited for the results of tests on the substance.

Two fire officers - dressed head to toe in yellow, plastic, protective suits - carried the envelope out of the building and put it through a chemical wash.

It was taken away in a sealed plastic bag at 8am by police to be driven to Government laboratories in Porton Down, Wiltshire, for analysis.

A West Yorkshire police spokesman said inquiries indicated that the white powder would prove "innocuous".

She said: "Initial inquiries have already been made with the addressee, which suggest the powder is non-hazardous, however it will be analysed as a precaution.

"While we believe that the substance will prove to be innocuous, we are carrying out investigations as a precaution and will be having samples from the envelope analysed.

"Some staff have been taken to hospital as a precautionary measure and the sorting office remains closed until we confirm what is in the envelope. Our steps are preventative at this stage.

She added: "We have no reason to believe it is connected with any terrorist activity either here or in the US, but obviously it is evidence that the current situation is making people more vigilant."

Odsal fire station hazardous materials adviser Alan Jones said: "We set up the decontamination procedures and isolated some postal workers who were in contact with the mail. We have got six postal workers that have been in close proximity.

"The envelope did contain an unidentified substance. We have to take precautions - this is the second incident we've had in West Yorkshire."

Divisional officer Robert Anderson from West Yorkshire Fire Service headquarters added: "Until we find out what it is, we have to take it seriously."

A Post Office spokesman said the building was evacuated in line with procedures which are taken whenever suspicious packages are found.

"We have procedures in place to deal with these situations which we are following today while we await to hear from the appropriate services on how to proceed."

He added that the building was expected to be closed for several hours and confirmed that no morning deliveries were made in the BD17 and BD18 areas today.

Staff, who had been sent home, would be called in later today to try to clear the backlog if the sorting office was given the all-clear.

The scare follows a spate of suspected anthrax alarms at postal sites in Liverpool, London, Northern Ireland and Scotland yesterday.

All of those incidents have since proved to be false alarms or hoaxes.

Shipley MP Chris Leslie, the Parliamentary Secretary at the Cabinet Office whose responsibilities include civil contingencies and emergency planning, said: "We must reiterate that our intelligence suggests there's still a very low actual risk of anthrax or other biological attack in the UK and that remains the case today.''

Mr Leslie called on people not to panic, adding: "To people in Shipley I'd say continue their usual day to day activities but obviously listen to any advice they may receive from the relevant authorities.

"There are bound to be worries from people finding packages and the advice is if they find a suspect package leave it alone and call the police who will deal with it. There are robust plans in place to deal with any situations.

"Potential recipients are being advised on how to recognise suspect packages and what to do if they receive one and while that advice is necessary it needs to be reiterated that there's no specific intelligence of any risk."

Police also urged the public not to panic as the scares sweep the country.

Scotland Yard said there was no intelligence of a "specific threat" of a biological or chemical attack but warned the public to be on their guard.

A spokeswoman said: "If people are suspicious of anything they have received in the mail or by hand they should contact police.

"The police will advise and assist them. We have asked people to be vigilant."

The Department of Health last night confirmed that it was preparing new guidance for NHS staff to help them deal with public concerns over anthrax.

A spokesman said that the guidance would be issued "shortly", but was unable to give a date for its release.

It is expected to help medical workers recognise and treat the disease, as well as allay the worries of members of the public frightened by the recent spate of cases in the US.

The latest anthrax alert was last night at a building in Millbank, central London, which includes BBC studios.

Scotland Yard said officers were called to reports of a suspicious substance in the reception area but the immediate area had already been evacuated by the building's occupants.

"Police are working to establish the source of the substance. Inquiries are ongoing," a police spokesman said.

A BBC spokesman added: "There has been an incident that police are investigating at No 4, Millbank. However we do not discuss security issues."

Also in London, 13 workers from the Stock Exchange were hosed down at a mobile decontamination unit after mail room staff became suspicious about a package yesterday morning. They were later taken to the Royal London Hospital in Whitechapel, east London.

Seven staff at the Westminster offices of the Local Government Association were quarantined inside two floors of the building in Smith Square yesterday after the alarm had been raised over a suspicious package received in the post.

The suspect packages at the London Stock Exchange and Smith Square were both tested and found to be harmless, a Scotland Yard spokesman said last night.

A similar scare hit a sorting office in Liverpool after a parcel containing powder was discovered.

The 400-strong workforce was cleared from the building, and six people who came into contact with the package were decontaminated and screened at hospital.

Tests later showed the substance leaking from the package in Liverpool was sand.

Merseyside Police said the package was opened in controlled conditions and its contents were found to be "totally innocent" and did not contain anthrax bacteria.

Police in Fife said a number of packages "purporting to contain anthrax" were delivered to various addresses yesterday, including St Andrews University where Prince William is a student.

But Assistant Chief Constable David Mellor said: "There is every likelihood that these fall more into the hoax category that we have previously experienced here in Fife than any direct connection with other events currently on-going elsewhere in the world."

A package also arrived at the Fife Constabulary headquarters in Glenrothes.

So far there have been no confirmed cases of anthrax being sent through the post outside the US.

The Public Health Laboratory Service confirmed that precautionary anthrax testing on three people in the UK has been completed and all three have tested negative.