AMMAN, Jordan (AP) _ A top Iraqi official who defected to Jordan this week may be plotting to overthrow his father-in-law and former mentor _ President Saddam Hussein.

Maj. Gen. Hussein Kamel al-Majid, long considered Saddam's right-hand man, has also been in contact with American officials and Iraqi opposition leaders in exile, sources said. A former Iraqi general said al-Majid was plotting to topple Saddam's regime.

Al-Majid defected Tuesday with other top Iraqi officials and was granted political asylum by Jordan's King Hussein.

The defection, which an American diplomat called the most serious since the Persian Gulf War, drew a vow by President Clinton to protect Jordan from Iraqi attack _ and the Iraqi response that no aggression would come.

A source at the U.S. Embassy in Amman said U.S. officials had contacted al-Majid. The source, who spoke on condition of anonymity, gave no details.

Al-Majid was in contact today with Iraqi opposition leaders in several countries, according to a Jordanian source who also spoke on condition of anonymity.

The source gave no details. But a former Iraqi general said in Damascus, Syria, that in a phone call, al-Majid told him he wants to topple Saddam's regime.

Maj. Gen. Wafiq al-Samarra'i, who defected to Syria in December, said Thursday that al-Majid told him he wants to meet Iraqi opposition groups, most of which are based outside their country, to ``agree on overthrowing the present regime in Baghdad.''

``We would support any step against Saddam's regime in order to rescue Iraq and its people,'' Al-Samarra'i said.

In the first official Iraqi reaction, Deputy Prime Minister Tariq Aziz denounced the defection and played down its significance, the Iraqi News Agency reported.

Aziz conceded al-Majid occupied an important post, but said: ``When he betrays his country and flees, he loses all weight.''

U.S. officials and Iraqi opposition leaders, however, have called the defection a major blow to Saddam's rule. Clinton said Thursday he would protect Jordan if the defections drew attacks from Baghdad.

Aziz called that an ``American hallucination,'' saying the idea of an Iraqi threat ``is only nonsense.''

Al-Majid has intimate knowledge of the inner workings of the regime, its weaknesses, security and military capabilities.

He has not made any public statements since he arrived in Jordan on Tuesday. He was accompanied by his wife, his brother and his sister-in-law. The women are Saddam's daughters. About 15 army officers also defected with the group. All were granted political asylum Tuesday by King Hussein.

Saddam's eldest son, Odai, traveled to Amman on Thursday to demand that return of the defectors, but the king refused to hand them over.

Travelers from Baghdad said the Iraqi government has tightened security in the capital following the defections, which underlined the economic and political toll of U.N. sanctions imposed in 1990 after Iraq invaded Kuwait.

Yet the travelers said there was no sign of trouble in Baghdad, where the state-run media has not yet mentioned the defections.

Hussein Kamel, who was the brains behind Saddam's clandestine weapons program, and his brother Saddam Kamel al-Majid, former head of the special security force protecting the regime, were holed up today in a heavily guarded farm outside Naour, 18 miles north of Amman, sources said on condition of anonymity.

One Iraqi source, a businessman with high-level connections in Baghdad, said al-Majid defected because he feared a crackdown on his clan was imminent.

The businessman, who also spoke on condition of anonymity, said scores of al-Majid's relatives and supporters were arrested two weeks ago by special security forces commanded by Saddam's youngest son, Qusai.

The al-Majid clan, long a pillar of the regime, has been locked in a power struggle with Saddam's half-brothers and his increasingly powerful sons.