No charges will be brought over the death of a 13-month-old boy who was killed by his grandparents' rottweiler.

West Yorkshire Police said there was insufficient evidence to secure a criminal conviction over the death of Archie-Lee Hirst, who was killed on December 28 by the family pet, which was described as weighing "in the region of seven to 10 stone".

The baby was spending Christmas at his grandparents' house in Wakefield, West Yorkshire, when the dog launched the unexpected attack.

Campaigner Elizabeth Hellmich, who founded Bradford's SAFE project and gathered a 1,000-name petition for the Government to toughen up the current legislation, said at the time: "The poor young girl who saw a dog rip apart her nephew will have to carry that with her for the rest of her life.

"How many more children have to die or be severely maimed before the Government and local councils address what is becoming a very serious issue?"

At the time of the attack, Archie-Lee's 16-year-old aunt was at home babysitting him and her two younger sisters, aged six and seven.

He was being carried by the seven-year-old when the dog, which was said to be used to children, snatched the child out of her arms. His aunt failed to save him, despite striking and kicking the dog, and he died later in hospital.

The rottweiler was later killed by police and is being examined by vets to establish why it acted so aggressively.