DAMASCUS, Syria - U.S. House Speaker Nancy Pelosi toured Damascus on Tuesday, the highest-ranking American politician to visit Syria since relations began to deteriorate four years ago. President Bush criticized the trip, saying it sends mixed signals to President Bashar Assad.

The United States accuses Syria of interfering in Iraq and Lebanon and sponsoring terrorists -- charges Syria denies. The Bush administration has resisted calls to open direct talks with Damascus on resolving the countries' disputes.

Pelosi, D-Calif., is scheduled to meet Assad and other Syrian officials on Wednesday. She made no comment on arrival and headed for the Old City of Damascus where she toured the 8th-century Omayyad Mosque.

Pelosi draped a scarf over her head as she entered the historic mosque and stopped at a tomb inside the mosque said to contain the head of St. John the Baptist. She made the sign of the cross in front of the tomb. About 10 percent of Syria's 18 million people are Christian.

In the nearby outdoor Bazouriyeh market, she chatted with Syrians, who offered her dates, in front of shops selling olive oil soaps, spices and herbs. At one point, she bought some coconut sweets and looked at Syrian carpets.

In Washington, Bush said visits to Syria by u.S. officials were "counterproductive."

"A lot of people have gone to see President Assad ... and yet we haven't seen action. He hasn't responded," he said at a Rose Garden news conference.

He said Assad had not reined in violent elements of militant groups Hamas and Hezbollah as requested by the international community and had acted to destabilize the democratically elected government of Lebanon.

"Sending delegations doesn't work. It's simply been counterproductive," Bush said.

Pelosi has shrugged off the criticism, pointing out that Republican members of Congress have also visited Syria. During a visit to neighboring Lebanon Monday, she said she considers the visits to be an "excellent idea" and was hopeful of rebuilding lost confidence between Washington and Damascus.

"We have no illusions but we have great hope," she said.

Syria treated the visit as a diplomatic victory. State-run newspapers published news of Pelosi's trip on their front pages, with one daily publishing a photograph of Pelosi next to the headline: "Welcome Dialogue."

But there were some warnings against high expectations.

Syria's ambassador to the United States, Imad Moustapha, described the visit as a "positive step" but said "it does not necessarily mean that the Bush administration would suddenly change its position" from Syria.

In comments to the state-run Al-Thawra daily published Tuesday, he said the visit should be a "reminder that even though we might disagree on politics, we should remain diplomatically engaged in dialogue to reach some understandings."

Pelosi is travelling with a delegation of U.S. lawmakers, including the first Muslim member of Congress, Keith Ellison, D-Minn.

In Israel, Pelosi said she would tell Syrian leaders that Israel will talk peace with them only if Syria stops supporting Palestinian militants. She has said she will also talk to the Syrians about Iraq, their role in neighboring Lebanon and their support for Lebanon's Hezbollah militants.

She accused the White House of singling out her Syria visit for criticism.

"It's interesting because three of our colleagues, who are all Republicans, were in Syria yesterday and I didn't hear the White House speaking out about that," Pelosi said Monday, referring to the Sunday meeting of Reps. Frank Wolf, Joe Pitts and Robert Aderholt with Assad in Damascus.

"I think that it was an excellent idea for them to go," said Pelosi. "And I think it's an excellent idea for us to go, as well."