(Bloomberg) -- The U.S. State Department issued a new travel warning for its nationals in Lebanon, citing political tensions and a threat of attack on American interests.

``The Department of State continues to strongly urge that Americans defer travel to Lebanon and that American citizens in Lebanon consider carefully the risks of remaining,'' it said in a statement posted on its Web site late yesterday. ``The U.S. remains concerned about the threat of terrorist attacks against Western and Lebanese government interests in Lebanon.''

Tensions have risen as a stalemate over the election of a new Lebanese president enters its six month, three years after the murder of former Prime Minister Rafiq Hariri plunged the country into crisis.

Lebanon hasn't had a president since Syrian-backed Emile Lahoud left office at the end of his term on Nov. 23. The pro- Western government of Prime Minister Fouad Siniora and pro- Syrian opposition of Shiite Muslim movement Hezbollah and Christian politician Michel Aoun have failed to agree on the succession. The dispute has generated the worst political tensions since the end of Lebanon's 1975-1990 civil war.

The State Department said al-Qaeda and the Palestinian Jund al-Sham group are active in Lebanon and have called for attacks on Western interests. Clashes such as those between Fatah al- Islam, an al-Qaeda-inspired group, and the Lebanese Army in northern Lebanon's Nahr al-Bared refugee camp last year could recur in other Palestinian camps, it said.

Damascus Bombing

In February, after the killing of Imad Mughniyeh, a commander of the Syrian-backed Shiite Muslim Hezbollah, by a car-bomb in Damascus, the U.S. Embassy in Beirut advised Americans to avoid all but essential travel and restricted the movement of its employees.

Hezbollah blamed Israel for Mughniyeh's death and its leader, Hassan Nasrallah, vowed to avenge him.

The U.S. Embassy issued its last warning March 6 advising U.S. nationals to keep a low profile and saying American interests may be a target.

In January, a U.S. Embassy car was hit by a bomb in a Beirut suburb that killed three Lebanese bystanders and injured 19 others.

France shut two cultural centers in Lebanon in February. Bahrain, Kuwait and Saudi Arabia advised their citizens the same month against traveling to Lebanon.

On April 15, the State Department issued a travel warning on Syria, saying that terrorist groups that oppose American policies operate there.

Syria has been designated since 1979 by the U.S. as a state sponsor of terrorism because of its support for Hezbollah, and for Palestinian groups such as Hamas and Islamic Jihad.

In September 2006, the U.S. Embassy in Damascus was attacked by terrorists armed with guns, grenades, and a car bomb that failed to detonate.

To contact the reporter on this story: Massoud A. Derhally in Amman, Jordan at mderhally@bloomberg.net.