Washington  - US President Barack Obama called on legislators to limit the number of pet projects for their own districts that are routinely included in spending bills, but refused to completely oppose the unpopular practice known as earmarks.

A renewed debate over the merits of earmarks has been swirling in Washington over the past few weeks as Congress debated a 410-billion- dollar budget for the remainder of the 2009 fiscal year, which ends in September.

Obama called it an "imperfect" budget because of some 5 billion dollars-worth of earmarks included in the spending bill, which was approved by the Senate Tuesday night. Opposition Republicans had strongly opposed the bill, though about 40 per cent of the earmarks were from their party's own members.

Obama will sign the legislation later Wednesday, which is necessary to keep government services running. But Obama said he would work with lawmakers to reform the process in future.

Earmarks "have been used as a vehicle for waste, and fraud and abuse," Obama said, but also noted that many local projects included through the process served a valuable purpose.

"Individual members of Congress understand their districts best. They should have the ability to respond to the needs of their communities," he said at the White House. (dpa)