ALBIREH, Lebanon (Reuters) - Hundreds of Islamist gunmen fired in the air on Monday at the funeral of a Sunni Muslim cleric whose killing ignited street battles and brought the bloodshed from Syria's 14-month-old uprising spilling across the border into Lebanon.
Sheikh Ahmed Abdul Wahid, an opponent of Syrian President Bashar al-Assad, was buried in northern Lebanon a day after he was shot dead at a Lebanese army checkpoint in a part of that country where Sunni sympathy for Syria's rebels and the uprising against Assad is particularly strong.
Demonstrators blocked roads and burned tires in the northern province of Akkar, and similar protests in Beirut gave way to firefights with machineguns and rocket-propelled grenades.
The clashes on Monday between gunmen from the Future Movement, loyal to anti-Assad former Prime Minister Saad al-Hariri, and members of a pro-Assad party, left two dead and was the worst unrest in Beirut since sectarian fighting brought Lebanon to the brink of civil war in 2008.
Violence flared later in the northern Lebanese city of Tripoli where two residents in Jebel Mohsen district, home to minority Alawites who support Assad, were wounded in rocket fire. Eight people were killed in Tripoli last week in fighting between Sunni Muslims, Alawites and the Lebanese army.
U.N. Secretary-General Ban Ki-moon, in a meeting with French President Francois Hollande, said he was "extremely worried" about all-out civil war in Syria "and the outbreak of related violence in Lebanon" according to a U.N. readout of their talks.
The U.S. State Department urged "all parties to exercise restraint and respect for Lebanon's security and stability".
Khaled Daher, a member of parliament from the Future Movement, said Abdul Wahid was the victim of an "intentional assassination" by Lebanese troops he said were loyal to Damascus.
Syria flooded Lebanon with troops early in its 1975-1991 civil war and dominated its smaller neighbor for over a decade afterwards. It retains significant influence over Lebanon's intelligence apparatus and military.
Mourners bore the bodies on Monday of Abdul Wahid and Muhammed Mraib, another man killed in the checkpoint incident, to a mosque in Albireh in Akkar, the coffin of the latter man shrouded in the standards of the rebel Free Syrian Army and the Future Movement.
Lebanon's prime minister, himself from Tripoli, has appealed for calm and promised steps to preserve civil peace. Judicial sources said 20 soldiers were being questioned over the checkpoint killing, following demands for their prosecution.
SYRIA SAYS UN IGNORING IMPACT OF SANCTIONS
In Syria, where a ceasefire intended to pave the way for a U.N.-sponsored peace plan has failed to take hold, opposition activists said Assad's forces extended an offensive in the central province of Hama.
Syrian forces shelled and then stormed the village of Qastoun on Monday, the head of the UK-based Syrian Observatory for Human Rights Rami Abdelrahman said, following what it said were the killings of 41 people a day earlier in nearby Souran.
Rami Abo Adnan, an activist living in Hama city, said he was hearing reports from residents of Qastoun that dozens of mortar bombs had hit the village and there were casualties.
The group claimed separately that two civilians had died of gunshot wounds on Monday after a skirmish between government troops and deserters outside the coastal city of Banias.
Opposition activists also said three rebels were killed in fighting in northern Idlib and Aleppo provinces, including Sheikh Issam al-Zein, a rebel commander. There was no independent confirmation of the accounts from Syria, which strictly limits journalists' access.
Damascus says it shares the U.N. plan's goal of a negotiated path out of bloodshed, and points to its recent constitutional change and parliamentary elections as proof of its sincerity. The opposition dismisses both as farcical.
The state news agency SANA said Assad called on the new parliament to convene on Thursday, and 16 members of the security forces killed by "terrorist" gangs were buried on Monday.
U.N. Under-Secretary-General for Peacekeeping Operations Herve Ladsous told reporters in Damascus that "a third element" was active in Syria - using a phrase which U.N. officials have employed to describe parties other than government forces or the opposition.
"Yes there are ... third elements and these people are not committed to the cause of the Syrian people," said Ladsous, who was in a convoy outside Damascus on Sunday when a roadside bomb struck 150 metres away.
"They are committed to their own agenda so we have to keep a watchful eye that what we are dealing with."
Syrian authorities say they are battling Islamist militants, including al Qaeda.
The government has clashed with the United Nations over the means of delivering humanitarian aid to about a million Syrians, with Damascus demanding control over the distribution of supplies. U.N. officials have said that might let Syria get into opposition strongholds and punish rebels by denying aid.
On Monday, Foreign Minister Walid al-Moualem told the U.N. peacekeeping chief that the global body should also show concern about the impact of Western sanctions on the wider Syrian population, SANA said.
"Expanding the scope of aid means that the (United Nations) cannot claim to care for the destiny of some one million Syrians affected by armed acts while ignoring 23 million Syrians whose livelihood and subsistence are targeted by European and U.S. sanctions," it quoted him as saying.