Hypothermia could claim the lives of rough sleepers this weekend if the sub-zero weather persists, a leading homeless charity said.

With the temperature expected to again plunge to -5 tonight Victoria-based charity, Housing Justice, says there is a 'high risk' of homeless people who are unable - or unwilling - to take hostel beds falling seriously ill.

A spokesman for the charity, which regularly counts the number of rough sleepers across central London, said: "We're very concerned for their welfare. There are are emergency shelters open but the people who are sleeping rough because they don't qualify for help or are unsure how to access it, are extremely vulnerable in these freezing conditions. Hypothermia is a real threat over the coming nights."

The government makes more emergency beds available in central London when the temperature falls below zero for three consequetive days. But rough sleepers need to prove they are homeless, something Housing Justice says can deter vulnerable people from taking up beds.

As the temperature dived below zero on Tuesday night there were five people bedding down on The Strand, in Westminster.

Martin, 48, who has been sleeping rough for six months, has is sitting out the big freeze on the street because few hostels will accomodate him with his seven-month old dog, Lilly.

He has a sleeping bag, a ski jacket and one jumper to fend off the chill.

"It's freezing at night. But it's just a question of toughing it out and hoping the weather improves," he said. "I wake up in the morning and my fingers are frozen, they feel like they will break."

Martin says the soup runs, the police and Westminster Council homeless team, are handing out extra sleeping bags, sweaters and hot drinks.

"People are really kind when it's cold, but I do worry I might go to sleep and not wake up."