British electricity network operators should push ahead with extra investments of up to £1bn to connect renewable energy sources to the grid by 2012, UK energy regulator Ofgem has announced.

Britain’s three electricity transmission companies, including National Grid, expect to invest £5bn in transmission projects over the next ten years.

Ofgem is concerned the companies might hold back on investing in infrastructure needed to connect wind farms and other clean energy projects until current controls on their investment spending run out in 2012.

The regulator plans to let the companies spend up to an extra 1 billion on key new projects over the next two years, it said in a statement.

About 90% of the investment is earmarked for Scotland where most wind projects are.

Scottish & Southern, which operates the transmission network in northern Scotland, could invest £200m in three upgrade projects from next year, the company said in a statement.