Gordon Brown was set for fresh conflict over his plans to build three million homes by 2020 after an independent report recommended building more homes in the South East than the limit set by local politicians.

Government-appointed inspectors recommended that 32,000 homes per year should be built in southeast England, 10 per cent more than the 28,900 total proposed by South East England Regional Assembly. The proposal was lower than many had expected, but even so the inspectors gave warning that it would mean treating green-belt land as inviolate “cannot be consistent with government policy”.

The Conservatives claimed that the report’s recommendations would mean concreting over large chunks of the green belt. Jacqui Lait, the Shadow Planning Minister, said: “Gordon Brown’s promise that he would protect the green belt has been exposed to be utterly worthless.”

A spokesman for the Department for Communities and Local Government said the Green Paper was “absolutely explicit that the current round of regional plans will not fully meet future need” but emphasised that there was no threat to green-belt land. The Conservatives said the panel had recommended reviewing green-belt protection in Blackwater Valley, Elm-bridge, Guildford, Oxford, Redhill and Reigate, Tandridge, Tunbridge Wells and Woking.

However, others suggested that the building targets would in fact be insufficient to meet the growing housing crisis in the South East. Stewart Baseley, executive chairman of the Home Builders Federation, said that the proposed 32,000-a-year limit “will not go anywhere near meeting the clear housing need in the region”.