The government could lose more than £100m on the Millennium Dome site if mayor Ken Livingstone pushes through plans to impose a 50 per cent affordable housing quota on the scheme, reports Building magazine.

Building says housing experts suggest that increasing the quota of affordable housing from 30 per cent, as it is now, to 50 per cent could decrease the value of the site by up to £100m. The magazine adds that it might also cut profit by £50m.

Under the terms of the joint venture deal with the Lend Lease Meridian Delta consortium, the government will receive cash equal to the value of the land as the developments are sold as well as half the profit.

The government said last month that it hoped to recoup £500m of the £600m it has spent on the site, but it is thought that this calculation was based on the assumption that 30 per cent of the site would be set aside for affordable homes, in line with Greenwich Council's planning regulations.

Livingstone is reported as saying he wants to raise that figure to 50 per cent, most of which would be pencilled in for social housing - which is particularly costly because of recent falls in subsidies for that sector of building.

Building says Meridian Delta believes it is not possible to quantify the impact of the affordable housing quota.