An urgent appeal has been launched to find a mother and her newborn baby after a woman gave birth in an underpass before being picked up by to men in a van.

The Metropolitan Police say the female reportedly gave birth at the Billet Road underpass, in Walthamstow, east London at about 8am on Wednesday.

The 'distressed' mother - thought to be a 'rough sleeper' - was aided in giving birth by a Good Samaritan, who had heard her cries and stayed with her.

The new mother was later picked up by two men in a blue transit van about eight hours later, at around 4pm, police say.

It's unclear if the men were known to the female, who was wearing a black dress, heavy jumper and is believed to be called Anne Marie.