The Bush administration charged yesterday that Syria has launched a campaign to politically and economically strangle Lebanon. The White House said Damascus is now blocking attempts by Beirut's new prime minister to form a government, while also threatening the livelihood of tens of thousands of Lebanese by closing the border to regional commerce.

U.S. and European officials alleged yesterday that President Bashar Assad's government now appears to be using new tools in an attempt to control the Lebanese because its ability to use military intimidation diminished after Syria was forced to withdraw 14,000 troops from Lebanon in April under international pressure.

Syria has blocked three attempts by the new Lebanese prime minister, Fouad Siniora, to form a cabinet after the historic May elections, undermining efforts to put in place a government that for the first time in 29 years would not be dominated by Damascus, U.S. officials said.

National Security Council spokesman Frederick L. Jones II charged that Lebanese President Emile Lahoud, a Syrian ally whose term was extended by three years under pressure from Damascus, is now "preventing the will of the Lebanese people from being carried out." Lahoud must approve the government, giving him veto power.

In an attempt to break a two-week deadlock, Siniora yesterday presented Lahoud with another proposed cabinet, which he said has the support of more than 100 members of the 128-member parliament.

Jones also said that Syria is now trying to "undermine the Lebanese economy by blocking Lebanese exports so that millions of dollars of produce rots" at the Lebanese-Syrian border. The number of trucks carrying agriculture and goods imported through Beirut's port to Syria, Iraq and Gulf countries has dropped from 300 per day to zero over the past two weeks, a State Department official said.

U.S. and European officials also charged that Syria has not pulled out a significant number of its 5,000 intelligence agents, who were also supposed to be removed from Lebanon by the end of April. A State Department official involved in Middle East policy said yesterday that there is "plenty of evidence" to suggest that Syria's hold on Lebanon is still strong.

"All these actions violate U.N. Resolution 1559, which calls for Syria domination and interference in Lebanon to end," Jones added.

The administration has also warned Syria that it is now consulting with other governments, including France, on ways to "force" Syria to halt its meddling and "reinforce Lebanese democracy and independence," Jones said.

Syrian Ambassador Imad Moustafa vehemently denied that Syria is playing any role in Lebanon, an accusation he described as "ridiculous" and said "does not merit a comment."

"Not a single Lebanese has complained that Syria is interfering in what is going on in the Lebanese political scene," he added. "The United States is the one that is interfering."

Border traffic has slowed because Damascus has introduced new border security measures, as it has along the Iraq border, he added. "Yes, the new security measures are causing some trouble for those who want to cross," he said, noting that Syrian officials pledged this week to try to streamline the new arrangements. "It is not an issue that warrants statements from the State Department. It will be addressed and resolved," he said.

But a State Department official yesterday countered: "It's not a question of a slowdown, inspecting and new measures that slow movement. This is a roadblock," he said speaking on the condition of anonymity because of the sensitive diplomacy underway.

The border closure is threatening 50,000 jobs in Lebanon, the official added, noting it would have a major impact on a country about 1,000 square miles smaller than Connecticut. The loss of produce exports has cost Lebanon $1.5 million, with a loss of $300,000 every day it continues, according to the State Department.

Syria also has taken some unusual steps to hurt Lebanon's economy, the State Department official said. A Lebanese mineral water company was banned from exporting to or through Syria because its metal bottle caps have six points, which resemble the six-pointed Star of David on the Israeli flag, and the water distributor in Syria has been jailed, he said.

"This is an obvious attempt to create an economic stranglehold on the most vulnerable sector of Lebanon's economy -- farmers and small merchants," the State Department official said. "Syria has historically been the gate through which Lebanese produce and products go to the rest of the region. Syria is now pulling out every dirty trick from its importation guide to have maximum dilatory effect."

The European Union is scheduled to hold a working session on the growing crisis in Lebanon on Monday in Brussels, according to a European diplomat involved in the meeting.

Terje Larsen, the United Nations' envoy to Lebanon, is to brief foreign ministers. Some E.U. members are pushing to put Syria on notice that any deepening of relations will depend on how helpful Syria is on Lebanon and the Palestinians, the diplomat said.

In the Bekaa Valley, east of Beirut, Lebanese children demonstrate against Syria's closing of its border crossings with Lebanon, which is blocking agricultural exports.