KUALA LUMPUR (Reuters) - Malaysia"s opposition pressed the government Monday to reveal results of probes into allegations that ex-finance minister Anwar Ibrahim was a U.S. spy.

Lim Kit Siang, national chairman of the Democratic Action Party, urged Prime Minister Mahathir Mohamad to reveal the outcome of three years of police and Anti-Corruption Agency investigations into whether Anwar was an agent for the U.S. Central Intelligence Agency.

"If after three years of intensive investigations, the authorities still come out with a blank, all those who had alleged in one form or another that Anwar was a CIA agent should have the humility and decency to publicly apologize for their calumny," Lim said.

The government had not replied as of late Monday. Mahathir is in Chicago for a meeting of leaders of developing nations.

Lim"s call for disclosure followed an article on a Malaysian online news site at the weekend by a former U.S. envoy to Malaysia, John Malott, who denied Anwar was ever a U.S. spy. Malott was ambassador in Kuala Lumpur when Anwar was sacked in September 1998 on allegations that included sexual misconduct and treason.

The day after Anwar"s sacking, local newspapers focused on allegations in a book by author Khalid Jafri that Anwar was a CIA spy, a homosexual and a womanizer during his last days in office. The spy accusations were taken up in parliament by Mahathir"s party members but Anwar was never charged with such an offense. "Anwar is no more an American spy than Mahathir Mohamad or Khalid Jafri," Malott said in the article on malaysiakini.com. Malott could not be reached for comment.

But Steven Gan, the editor of the online publication, confirmed that the former envoy, now retired in California, had written the article. Malott had called Anwar the world"s most prominent political prisoner after the ex-minister was sentenced to six years in jail in April last year for abuse of power.

Anwar, a Mahathir protege for more than a decade and prime-minister-in-waiting, was sentenced last month to a further nine years in jail for sodomy after a trial that split the country and stirred international condemnation. Anwar says he was dismissed and framed after a political fall-out with Mahathir. The prime minister insists he sacked Anwar for low morals and denies a conspiracy.