Plans to build 362,600 new homes across the West Midlands over the next 20 years, including almost certain intrusion into the green belt, have won the reluctant backing of local council leaders.

Members of the Regional Planning Partnership met in Birmingham yesterday to express severe doubts about targets for new dwellings, but accepted they could do little to resist Government pressure for a massive house building programme.

Most of the new-build will be concentrated in the major urban areas of Birmingham, the Black Country and Coventry, along with "settlements of significant development", which include Worcester, Redditch, Nuneaton and Bedworth, Rugby, Shrewsbury, Stafford, Warwick and Leamington and Hereford.

As many as 3,000 acres of green belt could be at risk, according to research carried out for the West Midlands Regional Assembly.

Consultants appointed by the WMRA raised concerns about the lack of social and economic infrastructure to support such a large number of new dwellings and expressed doubts about development on flood plains. They also warned the scale of development proposed in rural areas would worsen migration from cities to the countryside.

The RPP will meet again in October to approve a final submission to the Government.

It is unclear whether the proposed figure of 362,000 new homes will be acceptable to the Government, which has already said it wants to see at least 380,000 dwellings built over the period.

Yesterday's meeting heard a call from Birmingham city councillor Peter Douglas Osborn not to "kow tow" to the Government and to resist all green belt development.

Coun Douglas Osborn (Con Weoley) added: "We should decide there is a line that must not be crossed. We should say the brick stops here.

"There is a strong body of opinion that doesn't feel these figures are acceptable. If we are going to prevent concreting over more and more flood plain and back land development we must say the green belt is sacrosanct and we must have stronger conditions to prevent it being built on."

However, Coun Douglas Osborn's own local authority, Birmingham City Council, has already volunteered to build more houses than originally envisaged. The council says it will plan for 50,600 homes over the 20-year period.

Councils in Coventry and the Black Country have also indicated that they may accept a larger number.

Coventry is willing to consider "selective sustainable excursions" into the green belt.

Gerald Kells, a spokesman for the environmental sector on the WMRA, said there were "grave concerns" that infrastructure in terms of schools, hospitals and surgeries would not be sufficient to cope with the scale of development being planned.

Mr Kells said it would be better to have under-provision of new housing. The region could always build more homes if necessary, but the figures presently proposed would be irreversible once given Government approval.