WASHINGTON (AP) _ An American businessman says he was held against his will in Saudi Arabia for 133 days on spying charges and got a $400,000 check and his freedom only after he dropped a lawsuit against a Saudi businessman.

Sam Bamieh of San Mateo, Calif., told a news conference Wednesday that he had filed an affidavit a day earlier in U.S. District Court in San Jose, Calif., to revive the original lawsuit. In the new suit, Bamieh seeks $58.8 million in damages from two close associates of Saudi Arabian King Fahd.

Bamieh, who identifies himself as chairman of the board of directors of Industrial Development Group Inc., said he filed his original complaint last Feb. 25 against Saudi businessman Mohammed Imran, who is a retired head of Fahd's private offices. Bamieh said he sought damages resulting from Imran's alleged breach of a business partnership.

Bamieh did not go into detail about his business dealings in the Middle East except to say that his company is in ''the international marketing consulting business.''

He said he was on a business trip to Riyadh, Saudi Arabia, on Feb. 15, and was there when the complaint was served on Imran. Bamieh said he was warned the next day that he should drop the suit.

On March 4, he said, a Saudi official told him that King Fahd would like him to remain in Saudi Arabia so that he could see him when he returned from his desert camp.

He said he waited and tried repeatedly to set up an appointment with the king, who he said he already knew.

On April 1, he said, Imran told him that he must immediately withdraw his suit and that he was alleged to be working for the CIA and Israeli intelligence. Bamieh said he refused to drop the suit.

From May 12 until he left the country, he said, he was ''a 'guest of his Majesty,' which resulted in my being in 'protective custody' under 24-hour guard and-or surveillance at the Taif Conference Palace.''

Bamieh said he was the only guest in the 500-room palace. He said he was never tortured physically, but that his life was threatened and that he frequently was afraid to eat the food he was served.

After he withdrew the original suit and was about to leave Saudi Arabia, he was given a check for $400,000 from Shiek Mohammed al-Suliaman, which he said he accepted because he thought refusing it might delay his departure. But he said he wasn't told what the money was for. He said he previously had refused a briefcase full of Saudi money because he thought it might be part of a setup to discredit him.

In his new suit, Bamieh names as defendants Imran and al-Suliaman, the current head of Fahd's private offices, as well as about 50 other people whose identity he was still trying to determine.

Bamieh said that besides trying to force him to drop his suit against Imran, the defendants conspired to destroy his ability to conduct business in the Arab Middle East.