WASHINGTON – The Bush administration is sharpening its rhetoric against Syria, demanding it stop sponsoring terrorism and harboring remnants of Saddam Hussein’s Iraqi regime or face diplomatic or economic sanctions.

“It is time to sign on to a different kind of Middle East,” national security adviser Condoleezza Rice said Monday as Syria took another public pasting from the administration.

Secretary of State Colin Powell said Iraqis who have knowledge of weapons of mass destruction and Iraqi political leaders “are the kinds of individuals who should not be allowed to find safe haven in Syria.”

“And this is a point we have made to the Syrians directly and will continue to make to the Syrians,” he said at a news conference.

“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 declared. Raising the threat of punishment, he said, “We will examine possible measures of a diplomatic, economic or other nature as we move forward. … We’ll see how things unfold.”

In New York, U.N. Secretary-General Kofi Annan said he was “concerned that recent statements directed at Syria should not contribute to a wider destabilization in a region already affected heavily by the war in Iraq.”

Syrian officials denied having chemical weapons and said the United States has yet to prove similar charges against Iraq. They also accused Israel of spreading misinformation about Syria.

White House spokesman Ari Fleischer rejected those denials, calling Syria a rogue nation and saying it is “well corroborated” that Iraq’s neighbor has a chemical weapons program. “Syria needs to cooperate,” he said.

Rice, in a parallel thrust at Damascus, said Syria’s support for terrorism and “harboring the remnants of the Iraqi regime” were unacceptable.

But she indicated the administration was not contemplating military action.

Using the same formula the administration has applied to North Korea and its aggressive nuclear weapons program, Rice said at the Washington Institute for Near East Policy, “The president has made clear every problem in the Middle East cannot be dealt with the same way.”

And Powell signaled President Bashar Assad that the administration still would like to include Syria in the Mideast peacemaking it intends to accelerate between Israel and the Palestinians.

“As we go down the road to peace, we want it to be a comprehensive peace, and ultimately, of course, that would have to include finding a way to settle the outstanding issues with Syria, as well,” Powell said at a State Department news conference.

Syria seeks to recover the Golan Heights, a strategic area it lost to Israel in the 1967 Mideast War.

Although it long has been listed by the State Department as a sponsor of terrorism, ever since Richard Nixon’s presidency 30 years ago the United States has sought to interest Syria in peacemaking with Israel.

Itamar Rabinovich, who was Israel’s chief negotiator with Syria from 1992 to 1995, said its government wanted to please a radical constituency inside Syria but also would like to protect Syria’s relationship with the United States.

In a telephone interview, Rabinovich, now president of Tel Aviv University, said that over the years “the United States has been fascinated with the possibility of getting Syria to switch sides and become an ally of the United States.”

The administration’s strategy was to apply diplomatic pressure, he said, but “the bottom line is that I don’t think the United States plans to go to war with Syria.”

Assad met with British and Saudi envoys Monday in Damascus as his government denied U.S. charges that Syria has weapons of mass destruction and is sheltering Iraqi leaders.

Powell noted that Syria had said its border with Iraq was closed. However, he said, “it might mean the main roads are closed but whether or not others are able to get across the border is something that I can’t speak to.”

“But once they get into Syria and start heading to Damascus I would expect that Syrian authorities would do everything they could not to provide these people safe haven,” he said.

U.S. commanders said volunteers from Syria were among the foreigners helping Iraqis put up resistance against U.S. troops in Baghdad. Navy Capt. Frank Thorp, a Central Command spokesman, said the fighters were often working alone or in small clusters.