Ex-national security adviser Robert McFarlane, taking the stand Friday in Oliver North's trial, testified President Reagan never told anyone to lie to Congress about administration efforts to keep the Contra rebels in business.

McFarlane, who was sentenced last week for lying to Congress, strode into the courtroom of U.S. District Judge Gerhard Gesell and swore to tell the truth about North's secret activities on behalf of the Nicaraguan rebels after Congress had banned official U.S. aid to the CIA-formed force.John Keker, chief deputy to independent prosecutor Lawrence Walsh, began his questioning by recalling that McFarlane had been convicted exactly a year ago on four counts of withholding information from Congress.

The prosecution called McFarlane to prove that North lied to Congress in 1985 by drafting three letters - which McFarlane, as national security adviser, signed - that said North was not involved with the private efforts to aid the Contras.

When Congress voted in 1984 to cut off aid to the rebels seeking to overturn the Nicaraguan government, McFarlane told the jury, Reagan instructed him to "do all that we could to keep (the Contras) together body and soul."

McFarlane said he passed on those instructions to North, then his staff aide on the National Security Council.

"Did the president of the United States, Ronald Reagan, ever tell you to lie to Congress?" Keker asked.

"No," McFarlane said.

"About anything?"

"No," McFarlane replied.

Keker also delicately questioned McFarlane about his suicide attempt Feb. 9, 1987. McFarlane acknowledged he had tried to take his own life that day.

However, McFarlane probably will undergo blistering cross-examination by defense lawyer Brendan Sullivan, who is trying to show North - as an aide on the National Security Council - was always following orders from White House superiors.