Nama has rejected more than half of the business plans submitted to it by the top 10 developers in recent days.

A spokesman for Nama would not be drawn on the exact number of plans that have been sent back but confirmed that some have been returned to the developers because they are "simply not realistic".

Some of the plans had "not been adequately thought-out, require more work or are based on unrealistic assumptions," he said.

He added the agency was in contact with developers on a regular basis in relation to the plans and it is understood that there is daily contact between Nama and some of the developers. The top 10 developers owe about €16bn.

Nama will spend the next three months reviewing the plans that it has accepted with a view to making a final decision on whether the developers have the ability to repay their debts, to be made in late August or early September.

The asset management agency will then take legal action against those it deems to be insolvent and incapable of meeting their loan repayments.

Nama has signalled it may agree to debt-rescheduling and loan-restructuring in the case of borrowers which it believes could be viable within a three-to five-year timeframe. The transfer to Nama of the second tranche of loans, totalling about €13bn, will take place over the coming weeks and there is an expected transfer of about €8bn due to happen next month.

Nama chairman Frank Daly said last week he believes these loans would transfer at a similar 50% discount to that of the first tranche.

That would appear to rule out strong rumours which had been circulating that a tranche of loans totaling nearly €4bn was to have a 72% haircut and that the blended haircut in relation to 16 developers, with loans totaling more than €9.5bn, would be 66%.

Daly said last week that the "Irish banking system lent far too much to one sector of the economy, lent far too much to a small number of borrowers within that sector and is now paralysed into inertia as impairments build up and capital is depleted".