WORKERS are to begin erecting the country's biggest wind turbines in the North-East.

Energy company Powergen is building four windmills the size of London's Big Ben clock tower, on two remote sites in County Durham. They will be the largest and most powerful turbines to be built on the UK mainland.

A crane is in place to begin work on the first two structures, at Holmside Hall Farm in Craghead, near Stanley.

But engineers are waiting for ideal weather conditions before the delicate operation to raise the 100-metre tall windmills can begin.

A spokesman for Powergen Renewables said: "Work is due to start in the next few weeks, but it depends on the weather conditions.

"Ironically, they need very low winds along with very good visibility."

Two more turbines will go up at Crowshouse Moor, south of Harehill Farm, Haswell, near Durham.

Once they are in place, they will be connected to the national grid, then tested for 240 hours before being given the all-clear.

Between them, they will provide enough electricity to power 4,500 homes, reducing carbon emissions by 9,000 tonnes a year.

Durham City Council and Derwentside District Council granted planning permission for the two sites in 2000, with very little local opposition.

Powergen already operates 16 wind farms, producing enough power to supply 82,000 homes.

The new projects aim to increase the company's renewable capacity by 1,000MW by 2010.