Syria has arrested more than 1,200 people trying to cross the border into Iraq in recent weeks and sent many back to their home countries because of suspicions they were trying to join the insurgency, Syria's U.N. ambassador said.

Fayssal Mekdad (search) also denied rumors that terror mastermind Abu Musab al-Zarqawi (search) may be seeking shelter in Syria.

Mekdad said Syria suspected that those arrested — mostly foreigners — intended to carry out illegal activities in Iraq. They were sent back to Kuwait, Saudi Arabia, Libya and other countries, he said.

"We gave a lot of information to the United States on these issues, which prevented many attacks, but regrettably, the United States did not recognize such kind of help," he said in an interview.

Syria's ambassador to the United States, Imad Mustafa (search), said Tuesday that Syria had stopped security and military cooperation with the United States in the past few months after Washington failed to respond to repeated Syrian overtures. Mekdad said contacts continued "until a few weeks ago."

Syria provided the United States with intelligence on Al Qaeda after the Sept. 11 attacks. But President Bush ordered sanctions against Damascus a year ago after longstanding complaints that Syria was supporting terrorism and undermining U.S. efforts in Iraq — allegations it denies.

Secretary of State Condoleezza Rice (search) has steadily stepped up her rhetorical attack, from saying Syria was not doing enough to guard the border with Iraq to accusing it of permitting insurgents to stage their operations from Syria.

Syria has also been mentioned in speculation about the whereabouts of al-Zarqawi, the chief of Al Qaeda in Iraq, following an Internet statement on Tuesday calling on Muslims to pray for his life. Competing statements on his health and whereabouts followed.

The mystery deepened Wednesday after reports that two Arab doctors in another country were treating al-Zarqawi, who is wanted for some of the deadliest attacks in Iraq.

Mekdad denied any Syrian involvement with al-Zarqawi.

"These are silly rumor made by enemies of Syria — those who want to distort the image of Syria and its efforts to eliminate international terrorism," Mekdad said.

"This is meant to damage also the relations between Syria and Iraq, and the contribution of Syria to the Iraqi struggle against dictatorship," he said.

Speaking of terrorists trying to enter Iraq, Mekdad stressed that "Syria has never been friendly to such elements who are declared enemies of Syria as well."

The United States accuses Syria of harboring organizations Washington says promote terrorism, including Hamas (search) and Lebanese Hezbollah (search).

For 29 years, Syria also controlled much of Lebanon — but the Feb. 14 assassination of former Lebanese prime minister Rafiq Hariri (search) touched off anti-Syrian protests that led to last month's pullout of all Syrian troops from Lebanon.

A U.N. military team on Monday verified the troop withdrawal but said it couldn't be certain all intelligence operatives had left Lebanon.

State Department spokesman Richard Boucher said this issue remains "an open question" and that the U.S. will be looking at available evidence about Syria's possible intelligence presence and any attempts to exercise influence, especially in Lebanon's upcoming elections.

Syria views the verification team's report as "very positive," Mekdad said. "It confirms the withdrawal of Syrian troops, and intelligence apparatus and assets as requested by the Security Council."

"On our part, we have withdrawn everybody. We have done the maximum so there is no need to have any intelligence assets there," he said.

"Lebanon is an open country with an open media, and nobody has complained that there are any Syrian intelligence operatives there. If they do, we will take action immediately," Mekdad said.