"We will examine possible measures of a diplomatic, economic or other nature as we move forward," Secretary of State Colin Powell said as the White House branded Syria a "terrorist state" and a "rogue nation."

Powell did not say what sanctions would be considered but officials said Washington could consider recalling its ambassador to Damascus or otherwise downgrading diplomatic relations as it did once before in 1986.

Syria is already subject to some US sanctions as it is designated a "state sponsor of terrorism" by the State Department.

"They do, indeed, harbor terrorists. Syria is a terrorist state," White House spokesman Ari Fleischer said amid speculation that swift success in the war to oust Saddam was the opening shot in region-wide campaign.

On Sunday, US President George W. Bush charged Syria had chemical weapons and renewed the allegation that Syria has taken in remnants of Saddam's dismantled regime and his Baath party. Britain and Israel have made similar allegations.

"Do you think the White House and President Bush should look the other way at the fact that Syria is taking in Iraqi leaders?" Fleischer asked. "Do you think we should just ignore it? I think Syria understands our message."

Powell noted that Syria had pledged last week to close its border with Iraq to all non-humanitarian traffic but stressed that the border was porous and warned Damascus specifically against allowing any one of the 55 senior Iraqi official wanted by US forces to cross.

"These are the kinds of individuals who should not be allowed to find safe haven in Syria," he said, adding that if any of them had crossed the border, they should be detained.

"Once they get into Syria and start heading to Damascus, I would expect Syrian authorities would do everything they could not to provide these people safe haven," Powell said.

The secretary, as Bush and others have done, said the overthrow of Saddam's regime had fundamentally changed the environment in the Middle East and that support for terrorism or terrorist regimes as well as the pursuit of weapons of mass destruction would no longer be tolerated.

"We believe that in light of this new environment they should review their actions and their behavior, not only with respect to who gets haven in Syria and weapons of mass destruction but especially the support of terrorist activity," Powell said.

"We have a new situation in the region and we hope that all the nations in the region will now review their past practices and behavior," he said.

Syria has denied the allegations as France and Russia have both urged US restraint in dealing with the situation.

The United States withdrew its ambassador to Syria in 1986 and imposed administrative sanctions after evidence surfaced of direct Syrian involvement in an attempt to blow up an Israeli airplane.

The envoy returned a year later, in response to positive Syrian actions against terrorism, including the expulsion of the Abu Nidal Organization and its assistance in freeing a US hostage.

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