Frank Dunlop released

Property developers bribed some planners during the housing boom by offering them apartments at discounts of several thousand euro in return for planning permission, five senior industry sources have told the Sunday Tribune.

Before apartments went on sale, the planners would sign a contract allowing them to buy some at a discounted price. The following day the apartments would be sold on to unsuspecting buyers at the market price, with the planner pocketing the difference.

The practice is known as "flipping" and was widespread during the boom. However, until now it was not known that developers had used it to bribe planners. The scheme was "flawless", said one source, because of the near-absence of documentation.

Legal sources confirmed the transaction would not incur stamp duty because the tax applies to the transfer of a deed, not a contract. Buyers would be unaware of the transaction because the deed was unchanged and the developer acted directly with them afterwards. The only paperwork was between the developer and the planners, and this could be shredded.

One of the Sunday Tribune sources said a councillor in Dublin who "wanted a piece of the action" tried to get involved in the practice.

"When he heard I worked for [a named developer], he did come inquiring to me about payment through flipping of apartments or some scheme like that. I knew he was a crook and did not entertain him," the source said.

Three of the sources also fingered a former political figure, whom they dubbed "the new Frank Dunlop", as the mastermind of the scheme.

Dunlop was released from prison last week having served just over a year in prison after he admitted bribing politicians for planning permission.

A source in the Department of Environment said it was aware of the allegations but would require prima facie evidence to investigate.