AMMAN - A senior U.S. diplomat was gunned down with three bullets to the chest outside his Amman home on Monday, prompting outrage from the United States which condemned what it called an "incomprehensible act."

An unidentified assailant shot Laurence Foley, a senior administrator at the U.S. Agency for International Development (USAID), as he was leaving for work from his home in an affluent area of the Jordanian capital, officials said. It was the first assassination of a Western diplomat in Jordan.

No one immediately claimed responsibility for the murder of the 62-year-old American who started his 37-year public service career as a peace corps volunteer in India and has been in Amman with his wife Virginia since August 2000.

Foley was killed at a time of rising anti-American sentiment in the region amid perceived U.S. bias toward Israel and Washington's threatened military campaign against Iraq.

"We are outraged by this incomprehensible act," the U.S. embassy in Amman said in a statement. "The U.S. embassy has...reiterated our recommendation that all U.S. citizens remain vigilant in view of threats to American interests."

The statement referred to a U.S. government message issued on October 13 warning U.S. citizens in Jordan, a close U.S. ally, of a report that a member of Osama bin Laden's al Qaeda network had plans to kidnap Americans in the country.

A witness said he saw Foley's body lying outside his two-story villa "with blood near the driver's door of his Mercedes car."

U.S. ambassador to Jordan Edward Gnehm told reporters U.S. investigators were helping the authorities to search for the culprits, but said it was too early to make any assumptions about who was behind the killing.

TOUGHER SECURITY

New tougher security measures were also being adopted to protect U.S. diplomats after Foley's killing, Gnehm added.

"Jordanians have made absolutely clear that they are taking extraordinary steps and precautions that does include changing what they have done before," Gnehm added without elaborating.

In Washington, USAID administrator Andrew Natsios said: "Larry strove to make the world a better place than he found it. No one in USAID embodied the spirit of compassion that underpins our efforts more than Larry Foley."

A majority of Jordanians are of Palestinian origin deeply angered by U.S. policies in the region and what they perceive as double standards in dealing with Iraq and Israel.

There is also an outpouring of sympathy with Iraq, an Arab neighbor, main trading partner and oil supplier.

But Jordan, a country wedged between Israel on the west and Iraq on its eastern border, has grown in recent years more dependent on Washington's economic and political support.

This is in contrast with the 1991 Gulf War, when Jordan stood against the U.S. led military coalition that drove Iraq out of Kuwait.

Officials and diplomats have warned about the risk of alienating an increasingly disenchanted popular opinion by open support of President Bush's declared war on terrorism.

The kingdom was in the forefront of Arab countries that openly supported Washington's campaign against the former Taliban rulers of Afghanistan.

Over the last two years Jordan has seen an erosion of public liberties under tough laws that ban pro-Palestinian and Iraqi public demonstrations or street protest.

Officials have justified these laws as necessary to prevent radical elements such as Saudi-fugitive Osama bin Laden's Qaeda group from undermining internal stability.

But the mainstream Muslim opposition and independent politicians, who say the laws violate constitutional rights, have warned that increased curbs on public expression only encourage extremists to resort to acts of violence.

A Jordanian security official said Foley was shot at close range. "One assailant or more was behind the criminal shooting and investigations are ongoing to reveal the culprits," the official told Reuters, asking not to be identified.

Jordanian officials expressed shock and indignation at the first killing of a Western diplomat in the security conscious country, seen by many in the West as a model of stability in a volatile region.

Jordan has been rewarded this year with extra U.S. military assistance in return for its backing for Bush's war on terror. The country also ranks as the fourth largest recipient of USAID funds in the world.

In Washington, State Department spokesman Richard Boucher said the U.S. Embassy in Amman closed on Monday until further notice. He said Washington did not know who was responsible and could not be sure the killing was politically motivated.

But he linked it with "international terrorism," saying that tighter security was pushing attackers toward softer targets such as Bali nightclubs and Moscow theaters.