Police are hunting a man on a bicycle who carried out a serious sexual assault on a woman in Bradford.

A 33-year-old woman was walking in City Road, at its junction with Menstone Street, at 4am on Monday when she was approached by the cyclist.

The man took what is believed to be a knife from his rucksack and threatened the woman in an alleyway. He then subjected her to a serious sexual assault but she managed to get away uninjured.