A federal judge, accused last week of antigovernment bias, yesterday ordered the bribery trial of Airlie Foundation director Murdock Head to begin on Oct. 2, but did so without indicating whether he will preside at the proceedings.

Federal prosecutors had urged the 4th Circuit Court of Appeals in Richmond to remove District Court Judge Oren R. Lewis as the presiding judge at Head's upcoming trial, arguing that "Judge Lewis' angry attitude toward government counsel might well create an appearance of bias." The appeals court last week rebuffed the prosecutors' move.

During a brief court hearing yesterday in Alexandria, Lewis agreed to a request from the prosecution to delay the start of trial until Oct. 2 to allow time to subpoena witnesses. The prosecutors did not mention their previous objections to Lewis' alleged bias, and Lewis did not indicate whether he or another judge would preside at the trial.

Head, the founder and executive director of the tax-exempt Airlie Foundation near Warrenton, Va, has been charged with conspiring to bribe Rep. Daniel J. Flood (D-Pa.), former Flood aide Stephen B. Elko, former Rep. Otto E. Passman (D-La.) and a former Internal Revenue Service agent in an attempt to gain federal contracts, grants and favorable tax treatment for his foundation and other enterprises.

Prosecution and defense lawyers said yesterday that they expect testimony in the trial to last about 10 days. Head, who is also a George Washington University department chairman and physician, has pleaded innocent to the charges of bribery, conspiracy and tax evasion.

Although several pretrial hearings last month were marked by angry exchanges between the prosecutors and the 76-year-old judge, yesterday's court session was largely free of acrimony. Lewis did not require the prosecutors to drop any of the tax counts, as he had indicated he might, and he permitted the postponement of the trial despite a rule by the Alexandria court that trials must normally begin within 60 days after an indictment is returned.

Head's trial had been scheduled to start yesterday, but it was delayed because of the prosecution's unsuccessful appeal of a much-disputed ruling by Lewis to the circuit court.