The Government has been accused of "protecting builders" by not enforcing planning regulations which require 20 per cent of developments be made available for social and affordable housing.
Labour Party leader Mr Pat Rabbitte said since the regulations came into force in 2002 196,000 houses had been built but only 315 under the social and affordable housing provisions.
Speaking the Dáil, Mr Rabbitte claimed the Government was more concerned with protecting the builders than protecting people looking for social and affordable housing.
He said if the Planning and Development Act 2002 had been applied as intended more than 40,000 houses would have been provided.
But the Taoiseach said the Government had made a concession to property developers not to impose the terms of the Act on existing planning permissions.
This decision was taken, Mr Ahern said, because of the "very real fear that the housing supply would cease".
Record housing building in recent years was resulting in a far better balance between supply and demand, although problems remained with the Dublin region, he said.
The true impact of the Act only began to take effect in late 2002 and because the planning process could take between three to four years to complete, the full benefits were not yet apparent, he added.
Mr Rabbitte asked the Taoiseach for an update on the 10,000 social houses promised under Sustaining Progress.
Expressing some frustration at the slow pace of the project, Mr Ahern said State and local authority lands suitable for the construction of 8,900 houses had been identified and that the Department of Environment was working to identify sites for the remaining 1,100 houses.
"I wish they moved on quicker on these issues," said Mr Ahern, referring to county councils. He added that "once the initial planning stage is over perhaps we can go quicker."
Mr Ahern said the Government was spending almost €2 billion a year on social and affordable housing.
Last week the Department of the Environment confirmed that a one-off levy of 1 per cent on houses priced over €270,000 and 0.5 per cent on houses less than that was collected on only 400 of the 70,000 eligible homes.
