"If the enemy attacks our scientific, natural, human or technological interests, the Iranian people will cut off its hand without hesitation and place in danger the interests of the aggressor everywhere in the world," he told a gathering in the western city of Hamedan.

According to the official news agency IRNA, the all-powerful guide was responding to US allegations that Iran was damaging Washington's interests.

The United States, often simply referred to by Iranian leaders as the "enemy", accuses Iran of seeking to develop nuclear weapons, supporting terrorists and supporting insurgents in Iraq.

Meanwhile, Syrian President Bashar al-Assad yesterday ended a two-day surprise visit to Iran, after the two sides gave a show of unity against the presence of US troops in their common neighbour Iraq.

Assad, on his third visit to the Islamic republic, had met with a string of top regime officials here including supreme leader Ayatollah Ali Khamenei.

After meeting with President Mohammad Khatami, the two called for the rapid departure of foreign troops from Iraq.

"This crisis was predictable, and its source was the aggression and occupation of Iraq by the United States," Khatami said.

"There is no ambiguity between us and Syria where Iraq is concerned. The solution is the quick end to the occupation, the installation of a government comprising all elements of the Iraqi people and the cooperation of the international community to bring stability and reconstruction," he said.

For his part, Assad said "Iraq is on the top of our list of preoccupations" although he said his talks here would also cover "Palestine and the halt in the peace process".

"Regarding Iraq, we have always been in agreement with Iran on the need for Iraq's territorial integrity, a representative government and the departure of the occupying forces," he added.

Both Syria and Iran have been accused by the United States of supporting anti-coalition insurgents inside Iraq.

Just Monday, The New York Times quoted US government officials and a prominent Iraqi of saying a broad network of Saddam Hussein's extended family is helping fund and arm the anti-US insurgency in Iraq.

It said the network operates in part from Syria and Jordan and actively smuggles weapons, fighters and money into Iraq for the cause.

According to a British newspaper report Sunday, Iraqi Foreign Minister Hoshyar Zebari said his government had gathered information from intelligence services showing support for the insurgents from some neighbouring countries.

Zebari did not name the foreign powers, but the Sunday Telegraph quoted "senior Iraqi officials" as indicating "that Iran and Syria were the worst offenders".

Meanwhile, in a separate report, Syrian Information Minister Ahmad al-Hassan told the Iranian state news agency IRNA that Assad would discuss here the alleged presence of Israeli forces inside Iraq.

"Unfortunately, the Israelis are active in northern parts of Iraq and their presence poses a serious threat to Iranian and Syrian security," he was quoted as saying.

In June, the New Yorker magazine alleged that Israeli intelligence agents had infiltrated Iraq's Kurdistan and slipped across into Iran to monitor nuclear facilities.

Israel's embassy in Washington has denied the claim, but the magazine said a senior official at the US Central Intelligence Agency confirmed that Israelis are working for Iraq.

Assad, on his third visit to the Islamic republic since taking office in 2000, was accompanied by a high-level delegation, including Vice President Abdel Halim Khaddam and Foreign Minister Faruq al-Shara.

The Syrian president paid a short visit to Tehran in February 2003 on the eve of the US-led war against Iraq, after an earlier trip in January 2001.

Khatami last visited Syria during a May 2003 tour of Arab states.