WASHINGTON (AP) _ Former CIA spymaster Clair George ordered crucial information withheld from Congress as it investigated the downing of a plane involved in Oliver North's secret Nicaraguan supply network, onetime agency official Alan Fiers testified today.

''He said, 'look, that puts the spotlight on the White House or the administration or Oliver North','' Fiers told a federal court jury. He said George added, ''I don't want to be the first person to do that.''

George, the former head of CIA spy operations, is charged with lying to congressional committees by claiming he did not know who was behind a supply flight that was shot down over Nicaragua on Oct. 5, 1986.

George is being tried on three charges of obstructing Congress and a federal grand jury and six counts of perjury and false statements.

Fiers said George overruled his insistence that they would have to tell Congress they knew the real identity of a man called Max Gomez, who was publicly identified as being involved in the plane that had been shot down.

Fiers, the former chief of the CIA's Central American Task Force, said he told George, ''we're going to have to answer that Felix Rodriguez is Max Gomez.'' Rodriguez was a former CIA employee who had become an operative in North's network.

''He said, 'no, we're not going to say that. We're going to say we're still checking it','' Fiers told the seven-woman, five-man jury.

Fiers said George also ordered him to delete information about the supply network from a statement being prepared for the Senate Foreign Relations Committee briefing.

Fiers admitted he also did not reveal Gomez' true identity to the Senate panel.

''That was the script for the day and I was following the script for the day,'' he said.

He also acknowledged that he concealed information from House staffers who questioned him informally on Oct. 7, 1986, about the plane that had been shot down. He said he realized the incident could wind up uncovering North's entire secret operation.

''I was not truthful'' to the staffers, Fiers said. ''I essentially said that we didn't know the details, who was operating the aircraft.''

''Nobody directed me to do that,'' he said.

Fiers said he ''didn't have enough courage to put it on the record, and made a decision rightly or wrongly that I wasn't going to.''

Fiers pleaded guilty last year to two misdemeanor counts of withholding information from Congress.

Earlier, Fiers testified that George knew the full scope of the Iran-Contra affair months before it became a scandal.

Fiers testified Tuesday that North told him in August 1986 that the United States was selling arms to Iran and diverting the profits to support the Nicaraguan Contras.

Fiers said he reported this to George, who replied, ''Well, now you're one of a handful of people that know.''

In addition to the Iran arms profits, North's network used money from private benefactors to finance military aid to the Contras during a time when federal law barred such efforts by the CIA. However, the CIA was permitted to assist in a humanitarian aid plan authorized by Congress in 1985.

Fiers said that in February 1986 he and George discussed confusion among CIA officials in Central America about North's activities.

Fiers said George told him ''very clearly that this was a State Department- White House operation ... do not get involved in it.'' George sent him to Central America to give the same message to the station chief, Fiers said.

He vividly described how North's secret military supply network for Nicaragua took over the humanitarian aid effort by the State Department's Nicaragua Humanitarian Assistance Office.

While in El Salvador, Fiers said he met North operative Felix Rodriguez, who was supervising the loading of a plane with a ''great big U.S. flag on the tail.'' Fiers said he objected to use of the U.S.-marked plane, but Rodriguez would not stop the flight until he spoke by phone to North.

Fiers said he spoke with a Nicaragua Humanitarian Assistance Office pilot, Richard Gadd, who ''left no doubt in my mind that he was the NHAO contractor by day, the private benefactor by night.''

Fiers said George and other officials, including President Reagan, were aware that North was operating in Central America.

Fiers said he attended a May 1986 meeting of the National Security Policy Group chaired by Reagan, at which officials were discussing how to continue providing humanitarian aid to the Contras after congressionally authorized funds ran out.

''The president said, 'What about Ollie's people? Can't they help?''' Fiers said.