The league, headquartered in the Egyptian capital, expressed its "grave concern," while an advisor to Egyptian President Hosni Mubarak warned the Americans against the temptation to "target one Arab country after another", reported Agence France-Presse (AFP).

Arab League Secretary General Amr Mussa called the U.S. accusations that Syria was harboring members of the Iraqi regime who had fled across the border and was in possession of chemical weapons "very serious".

"The Arab League expresses its grave concern at these threats," Mussa said. "Threats of this nature against an Arab country and a member of the UN Security Council astound us."

Meanwhile, Osama al-Baz, Mubarak's top political advisor, said: "The attempt by the United States to target one Arab country after another will do great harm to the Americans' image."

Such accusations against Syria "after things have started to calm down in Iraq", will "give Arabs the false impression that they are the target, one after the other, and that Iraq was only a first step," he added.

Baz underlined the "great difference between Syria and Iraq under Saddam Hussein" and added that Egypt knew perfectly well that Syria did not have any chemical weapons.

"Let them prove it," he said. "I am sure the Syrians would react favorably to any attempt to verify that their country was not harboring such weapons."

In Damascus, Syria, under such growing pressure from U.S. President George W. Bush to "cooperate" on Iraq and accused of harboring chemical weapons, rejected the string of charges coming out of Washington.

Imad Moustapha, the number two at the Syrian embassy in Washington, flatly denied U.S. accusations that Syria was assisting members of Saddam's regime, harboring terrorists or producing weapons of mass destruction.

He said Syria was willing to accept international inspections to allay U.S. fears that it has weapons of mass destruction and urged Washington to help rid the entire Middle East - including Israel - of such arms.

Since late March, U.S. warnings to Syria have been almost daily events, escalating in the past few days into a high-profile test of strength between the two countries.

Top U.S. leaders, including Secretary of Defense Donald Rumsfeld, Secretary of State Colin Powell and Rumsfeld's deputy Paul Wolfowitz, have sounded a chorus of veiled threats to Damascus, charging it consistently aided the toppled regime of Saddam Hussein.

Help by Syria's Baath Party to its now-ousted Iraqi namesake has taken several forms according to the United States, from aiding Syrian volunteers fighting in Iraq to shipments of military supplies and providing asylum to fugitive Iraqi chiefs.

More worrying, Washington accuses Damascus of taking in Iraqi chemical weapons that have escaped detection by coalition troops ostensibly sent to Iraq with the aim of eliminating alleged weapons of mass destruction.

The latest interventions by President George W. Bush have taken the affair to a higher plane.

On Friday, he demanded "total cooperation" by Syria in capturing Iraqi leaders who allegedly crossed the border since U.S.-led occupation troops began their push to oust Saddam Hussein.

Faced with such veiled threats, Syria protests, and suggests Washington is biting off more than it can chew.

"We are the victims," Foreign Minister Faruq al-Shara declared Saturday during a joint press conference with visiting French counterpart Dominique de Villepin.

"The United States already has a lot to do. They have Iraq on their hands after Afghanistan.

"But they have not even been able to solve the Afghan problem. They have not been able to find bin Laden despite their sophisticated means," he joked in a reference to wanted al-Qaeda leader Osama bin Laden.

Because the United States "have not found weapons of mass destruction in Iraq despite their accusations, (they) are now targeting other countries with the same allegations," Shara charged.

In Washington, a senior Syrian embassy official told NBC television: "There is a campaign of false information and disinformation against Syria which began even before the war."

Damascus is getting backing from regional officials such as Amr Mussa, who the official Syrian daily Tishrin said Monday considered "groundless the accusations of certain American leaders against Syria."