A corruption inquiry has heard that property development company Brickworks continued paying for a researcher in the office of then Opposition Leader Barry O'Farrell after laws were passed in NSW banning political donations from developers.

Robert Webster, a director of Brickworks and former minister in the Greiner government, told the Independent Commission Against Corruption on Thursday that the company was "approached by the Liberal Party to provide funding for a researcher because the leader's office was under-staffed".

Barry O'Farrell at ICAC this week. Credit:Getty Images/Daniel Munoz

He said the arrangement was approved by the board in about 2008 or 2009 and $150,000 was paid over three years.

Junior counsel assisting the commission, Greg O'Mahoney, said the ICAC had information that some of the money was paid after the state parliament passed laws in December 2009 banning donations from developers.