By Douglas Jehl and Thom Shanker
New York Times News Service

WASHINGTON — Syria has halted military and intelligence cooperation with the United States, its ambassador to Washington said in an interview, in a sign of growing strains between the two nations over the insurgency in Iraq.

The ambassador, Imad Moustapha, said in the interview on Friday at the Syrian Embassy here that his country had, in the past 10 days, "severed all links" with the U.S. military and Central Intelligence Agency because of what he called unjust American allegations. The Bush administration has complained bitterly that Damascus is not doing enough to halt the flow of men and money to the insurgency in Iraq.

Moustapha said he believed that the Bush administration had decided "to escalate the situation with Syria" despite steps Damascus has taken against the insurgents in Iraq, and despite the withdrawal in recent weeks of Syrian troops from Lebanon, in response to international demands.

He said American complaints had been renewed since February, when a half-brother of Saddam Hussein, who was once the widely feared head of Iraq's two most powerful security agencies, was handed over to the Iraqi authorities after being captured in Syria along with several lieutenants. The renewal of complaints caused Syria to abandon the idea of providing further help, he said.

"We thought, why should we continue to cooperate?" he said.

Bush administration officials said Syria's stance has prompted intense debate at high levels in the administration about new steps that might be taken against the Damascus government. The officials said the options included possible military, diplomatic or economic action. But senior Pentagon and military officials cautioned on Monday that if any military action was eventually ordered, it was likely to be limited to insurgent movements along the border.

"There's a lot of discussion about what to do about Syria and what a problem it is," said the administration official, who works for a government agency that has been involved in the debate.

Relations between Syria and the United States have been souring for months, and some Bush administration officials said that Syria's level of cooperation had been dwindling even before the latest move.

Lawrence Di Rita, the Pentagon spokesman, said that there has been occasional low-level military-to-military communications along the border. He said the Defense Department had received no official notification of a change in that status, nor that the status of American military attaches in Damascus had been altered.

The American officials declined to provide an on-the-record response to Moustapha's statements on halting intelligence cooperation, citing the delicacy of the issue. American intelligence officials have said that Syria has provided important assistance in the campaign against al-Qaida since the attacks of Sept. 11, 2001. In recent months, senior Pentagon officials and military officers say, cooperation between the two nations has included low-level communications across the border between captains and field-grade officers of the American-led alliance and their Syrian counterparts.

One senior military officer said these communications had been helpful in mitigating a number of "cross-border firings" of artillery that have occurred between Syrian forces and the American-led military in Iraq. Any further scaling back of cooperation there or between Syria and the CIA could have a tangible impact, officials said.

American military officers in Baghdad and intelligence analysts in Washington say that militant cells inside Iraq draw on "unlimited money" from an underground financial network run by former Baath Party leaders and relatives of Saddam, many of whom they say found safe haven to live and operate in Syria.

These officials say that Damascus has done very little in its banking system to stop the funds, nor has it seized former Iraqi Baathists identified by the United States as organizing and financing the insurgency.

In presenting Syria's case, Moustapha said his government had done all it could to respond to American complaints, including taking steps to build barriers and add to border patrols.

He declined to comment on any role Syria might have played in the capture of Sadam's half-brother,

Sabawi Ibrahim al-Hassan al-Tikriti, No.36 on the American list of 55 most-wanted Iraqis. But the ambassador said that Syria had jailed some 1,200 foreign fighters who sought to enter Iraq from Syria, and had returned scores of others to their home countries.

On the day of the interview with Moustapha, Secretary of State Condoleezza Rice said Syria was "allowing its territory to be used to organize terrorist attacks against innocent Iraqis."

Syria's border with Iraq has become an increasing focus not just for policy makers, but for American military commanders in Iraq, who have made it a center of a recent offensive in western Iraq that was aimed at insurgents believed to have entered the country from Syria.

A senior American military officer acknowledged that "the Syrian government has in some cases been helpful" in building border berms and otherwise taking action against people involved in providing support to the insurgency. But the officer added: "Our sense is that they protest a bit too much and that they are capable of doing more. We expect them to do more."

The U.S. ambassador to Damascus, Margaret Scobey, has been in Washington for several months, having been recalled for consultations after the assassination in Lebanon on Feb. 14 of Rafik Hariri, a former prime minister. Syria has long been a dominant political force in Lebanon, and the question of whether its security forces were involved in Hariri's killing is still being investigated.