The United States Monday publicly called on Syria to do more to curb the traffic of foreign fighters to Iraq through Syrian territory. The transit to Iraq of foreign extremists, which had been reduced to a trickle in recent months, is reportedly increasing again. 

The Obama administration has confirmed that senior U.S. envoys in Damascus last week made a direct appeal to Syrian authorities to again crack down on cross-border traffic of Arab militants, some of whom have apparently been involved in recent suicide bombings in Iraq.

The flow of foreign fighters through Syria to Iraq, which reportedly peaked at several dozen crossings a month in the middle of 2007, had been a major irritant in U.S.-Syrian relations.

The Washington Post newspaper quoted U.S. military officials as saying that the traffic, which had nearly ceased early this year, has increased again to about 20 individuals a month. It said that at least two Tunisian men who had been smuggled across the border in April, staged suicide attacks in Iraq only days later as part of a bombing offensive by the group al-Qaida in Iraq.

At a news briefing, State Department Spokesman Ian Kelly said the issue had been raised during a visit to Damascus last week by Acting Assistant Secretary of State for Near Eastern Affairs Jeffrey Feltman and White House National Security Council Middle East expert Daniel Shapiro.

"We continue to have very deep concern about this issue, of the flow of foreign fighters going into Iraq via Syria," he said. "And we also continue to call on Syria to take immediate and decisive action, including better screening of individuals entering Damascus airport, increased security on the Iraq-Syria border, better cooperation with the government of Iraq in denying foreign fighter-facilitators safe haven in Syria."

There have been similar expressions of concern in recent days by the head of U.S. Central Command, General David Petraeus, and U.S. military commander in Iraq, General Raymond Odierno, neither of whom directly accused the Damascus government of supporting the traffic.

The Obama administration is trying diplomatic outreach to Syria, in hope of persuading the Damascus government to distance itself from Iran and end support for radicals in the region such as Lebanon's Hezbollah movement and the Palestinian group Hamas, which controls Gaza.

The Damascus visit by U.S. officials Feltman and Shapiro was their second in two months, and U.S. Middle East envoy George Mitchell is understood to be considering his own visit there if the outreach effort is productive.

There is no early indication of that, however, with Syria and Iran reaffirming their alliance during a Damascus visit by Iranian President Mahmoud Ahmadinejad a week ago.

Late last week, President Obama extended for another year a set of economic sanctions against Syria imposed by former President Bush under a 2003 act of Congress.