UNITED NATIONS — Lebanon’s border with Syria is highly “penetrable,” a U.N. team of border control professionals is concluding, bolstering Israeli claims that Hezbollah is rearming.

Members of the U.N. Security Council yesterday received copies of the team’s report, even as they deliberated an extension for the U.N. Interim Force in Lebanon, deployed in the aftermath of the 2006 war between Israel and Hezbollah, a Shiite organization backed by Iran and Syria. The head of the peacekeeping force said recently that no weapons violations had occurred inside his area of command in southern Lebanon, Hezbollah’s main area of operation.

“Lebanon has not yet succeeded in enhancing the overall security of its borders in any significant manner,” the four-person Lebanon Independent Border Assessment Team, led by a Danish security expert, Lasse Christensen, said in its 27-page report.

The council established the team, known as Libat, in 2007 in an effort to enforce council resolutions calling for an end to unauthorized weapons smuggling into Lebanon from neighboring countries.

Last year, after visiting Lebanon for the first time, Libat reported that the country’s borders and sea and airports were porous and that the Syria-Lebanon border in particular was vulnerable to arms smuggling. When the team members visited Lebanon again late last month, they found that there had been “virtually no progress” along the Syrian border. The border “remains as penetrable” as it was in 2007, despite the team’s strong recommendations that Lebanon improve its border security, it said in the report.

Israeli military officials have long argued that the open border allows an uninterrupted flow of weapons to Hezbollah, especially in southern Lebanon, where Unifil has been deployed since the 2006 war. Unfil’s commander, Major-General Claudio Graziano of Italy, told The New York Sun two weeks ago that Hezbollah had committed no major weapons violations in his area of command, while Israel continuously violated Lebanon’s airspace by conducting flights across the border.

“The presence and massive redeployment of armed Hezbollah elements and their acquisition of capabilities, both north and south of the Litani River, along with the continuous transfer of weapons from Iran and Syria to Hezbollah, are a blatant violation of resolutions,” an Israeli U.N. ambassador, Daniel Carmon, told the Security Council yesterday. Speaking as the council unanimously extended the mandate of Unifil for a year, Mr. Carmon said Israel expected the U.N. force “to ensure that its area of operations is not utilized for hostile activities of any kind and to resist attempts to prevent it from discharging its mandate.”

That task, as the new Libat report demonstrates, “is indeed a big challenge,” Mr. Carmon told the council, adding: “For us, this is a major concern.”