The Los Angeles city-county joint powers authority that oversees downtown’s Grand Avenue mixed-use project on Monday gave the project’s developer a two-month extension for the start of construction.

The $3 billion development originally was slated to break ground this spring, but in April the developer Related Cos asked for an eight-month delay, which the Grand Avenue Committee had been widely expect to approve on Monday.

Instead, the board the developer was given a 60-day deferral, which could be further extended at another meeting, said Martha Welborne, managing director of the Grand Avenue Committee. “There were more details to work out that we haven’t worked out.”

The project, which in its first phase will include residential buildings, a hotel and a retail center, has been delayed several times since fall 2007. Downtown interests have been concerned that last summer’s credit crunch and the ongoing housing slump could dampen interest in the redevelopment project.

Related, which earlier this year secured $100 million in equity financing from Istithmar, the investment vehicle of Dubai’s royal family, said it is on track to start construction in spring 2009.

“The JPA is responsible to make sure that it has all the information it needs to monitor progress which we understand,” said Bill Witte, president of Related of California, a unit of New York City-based Related. “In the meantime, we are going full speed ahead with construction documents and our commitment is now at over $90 million and growing every day. We would not be moving forward with The Grand if it didn’t make sense.”