"We will examine possible measures of a diplomatic, economic or other nature as we move forward," Secretary of State Colin Powell said in comments indicating greater attention on Syria as the Iraq war comes to an end.

The White House, meanwhile, branded Syria a "terrorist state" and a "rogue nation" and Defense Secretary Donald Rumsfeld said Syria has conducted a chemical weapons test during the past 15 months.

"We have seen a chemical weapons test in Syria over the past 12, 15 months," he said in response to Syrian denials that it has chemical weapons.

Rumsfeld said the United States also has intelligence that Syria has allowed Syrians and others enter Iraq with arms and leaflets indicating that they would be rewarded for killing Americans.

The secretary of state did not say what sanctions would be considered but officials said Washington could consider recalling its ambassador to Damascus. It could also downgrade diplomatic relations as it did once 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.

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, all denied by Syria and other Arab states have also expressed concern at the mounting pressure on the Damascus regime.

British Prime Minister Tony Blair said Monday that Syria's President Bashar al-Assad has promised his country will stop fleeing Iraqis from crossing its border.

And Blair told the House of Commons that Britain and the United States had no plans to invade Syria, despite the US charges that senior Iraqi regime figures were taking refuge in the country.

"I spoke with President Bashar al-Assad over the weekend and he assured me that they would interdict anybody who's crossing over the border from Iraq into Syria," Blair said, adding: "I believe they are doing that."

The United States has been taking an increasingly hard line on Syria however.

"Do you think the White House and President Bush should look the other way at the fact that Syria is taking in Iraqi leaders?" the White Hose spokesman 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 he again warned Damascus specifically against allowing any one of the 55 senior Iraqi officials -- led by Saddam and his sons -- 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.

"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 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.

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 Syrian actions against terrorism, including the expulsion of the Abu Nidal Organization and its assistance in freeing a US hostage.

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