Emergency teams are working to evacuate people from homes in York, as flooding continues to hit northern England. More than 7,500 homes are left without power. Prime Minister David Cameron has just chaired an emergency meeting to address the environmental disaster that has hit most part of North London.

Police advised between 300 and 400 people to evacuate near the River Ouse and River Foss in York, with up to 3,500 properties at risk.

Hundreds of flood alerts and warnings are in place for England, Wales and Scotland, including more than 20 severe warnings – indicating danger to life.

PM David Cameron said the flooding was unprecedented and promised more troops.

After chairing an emergency conference call, the prime minister said the situation for many was “incredibly serious”.

“The level of the rivers plus the level of rainfall has created an unprecedented effect, and so some very serious flooding,” he said.

“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.

In York, officials said pumps at the Foss Barrier – where the River Foss joins the River Ouse – had been overwhelmed and flood barriers had to be lifted, meaning areas of the city that would usually be protected were now vulnerable to flooding.

York City Council said the River Ouse was expected to peak at more than 5m – close to to its highest recorded level of 5.40m.

The Environment Agency said the River Ouse’s water level had reached 4.65m at 04:00 GMT on Sunday. Its typical level is between 0.5m and 1.9m.

Police say the flood operation in Greater Manchester has now turned to “a recovery” phase, as water levels begin to drop.

More than 7,500 customers in Greater Manchester and Lancashire remain without power, Electricity North West said, including 5,500 homes and businesses in Rochdale.