Some 500 soldiers have now been brought in to deal with “unprecedented” flooding in Yorkshire and Lancashire.

A thousand more are on stand-by after David Cameron vowed to help people in “their hour of need”.

Rescuers have been evacuating homes in York where water levels are still rising, and thousands of people in north-west England are without power.

There are scores of flood warnings in England, Wales and Scotland – more than 20 severe, meaning danger to life.

On Sunday, the government said it was deploying a further 200 soldiers to affected areas on top of the 300 who were already on the ground.

After chairing an emergency conference call of the government’s emergency committee Cobra, the prime minister said the “level of the rivers plus the level of rainfall has created an unprecedented effect, and so some very serious flooding”.

“We will do everything we can to help people in this, their hour of need,” added Mr Cameron, who is expected to visit some of the flood-affected areas on Monday.

City of York Council said the River Ouse was 5.1m above normal summer levels and was expected to peak around lunchtime on Monday – close to its highest recorded level of 5.4m.

It said about 500 properties were directly affected by flooding and a second rest centre was being opened for residents.

Meanwhile, North Yorkshire Police is urging people not to travel to flooded parts of York, as well as the Selby area, where the Ouse has burst its banks and is threatening homes in the village of Cawood.

Leeds has also been badly affected, with 1,000 homes flooded, but the city’s council leader said the government had been warned “a major flood… was a catastrophe waiting to happen”.

“While now is the time to focus on the wellbeing of our residents and the condition of their properties and possessions, we will again be calling on the government for further significant investment in additional flood defences,” Judith Blake added.

Downing Street said emergency financial assistance would available to homes and businesses in Yorkshire and Lancashire, and they would have access to the support package announced earlier in the month for people affected by Storm Desmond in Cumbria.

Flood-damaged infrastructure – including the A591 through the heart of the Lake District – will be repaired using £40m in emergency government funding, said Transport Secretary Patrick McLoughlin.