London, Dec 23 (IANS) Britain's Prince William was nearly run over by a road sweeper vehicle when he spent the night sleeping rough in minus four degrees celsius for a charity in London this week.

William, 27 and the second line to the British throne, curled up inside a sleeping bag on cardboard boxes next to plastic rubbish bins to highlight the plight of the homeless.

But a local council cleaning vehicle almost ran over him as he slept in a central London alleyway.

'I cannot, after one night, even begin to imagine what it must be like to sleep rough on London's streets night after night,' said the prince, clearly shaken by the experience.

'Poverty, mental illness, drug and alcohol dependency and family breakdown cause people to become and then stay homeless.'

Seyi Obakin, head of the homeless charity Centrepoint who joined William on the challenge, said later sleeping rough is 'scary.'

'The hairiest moment was when we were almost run over by a road sweeper which didn't see our small group huddled together, which shows how vulnerable rough sleepers are,' Obakin said.

At 6 a.m. William went to a homeless centre, where he cooked breakfast for some young homeless people.

His interest in Centrepoint, which has its 40th anniversary this year, was inspired by his mother Diana, who was its patron and often took William and his brother Harry on her visits to the homeless.