The Labour Party is to table a Dail motion asking the Tanaiste, Ms Harney, to order the Competition Authority to investigate the home loans market.
The motion will ask the Tanaiste to use her powers under Section 8 of the Competition (Amendment) Act, 1996, to request the Competition Authority to study and report on the practices and methods in the setting of mortgage interest rates over the last year.
It specifically asks that the Competition Authority investigate whether any agreements or concerted practices existed between mortgage companies.
The Labour Party spokesman on finance, Mr Derek McDowell, said most, if not all, of the financial institutions had responded quickly to the new rates set by the Bank of Scotland.