Syria warned it may strike at rebels hiding in neighboring Lebanon if the Lebanese army does not act, the state news agency SANA said on Friday, the second anniversary of the civil war.
Syria's Foreign Ministry told its Lebanese counterpart late on Thursday that a "large number" of militants had crossed Lebanon's northern border into the Syrian town of Tel Kalakh over the past two days, SANA said.
"Syria expects the Lebanese side to prevent these armed terrorist groups from using the borders as a crossing point, because they target Syrian people and are violating Syrian sovereignty," the diplomatic cable said.
It said Syria's "patience is not unlimited," even though "Syrian forces have so far exercised restraint from striking at armed gangs inside Lebanese territory."
Fighting near the border resulted in a large number of casualties, SANA said, before the gunmen retreated into Lebanon.
Lebanon has a policy of "dissociation" from the two-year civil war in Syria but officials say they feel their country is increasingly at risk of being dragged into a conflict that the United Nations says has killed 70,000 Syrians.
Threat to Lebanon's existence
U.N. refugee agency chief Antonio Guterres said on Friday that the Syrian conflict threatens Lebanon's existence.
"The international community should recognize that the Syrian crisis represents an existential threat to Lebanon and should show Lebanon ... much stronger support than has happened until now," he told reporters in Beirut.
Lebanon, a nation of 4 million, fought its own devastating civil war from 1975 to 1990 and has sectarian tensions among Christians and Sunni and Shiite Muslims that have been heightened by the fighting in Syria.
Tensions between Lebanese groups that support the Syrian opposition and those that support Syrian President Bashar Assad have been intensifying and have sometimes turned violent.
The International Committee of the Red Cross appealed to foreign powers Friday to press combatants in Syria to halt attacks on civilians and aid workers, saying all sides were violating the Geneva Conventions.
"Many atrocities against civilians have been reported or witnessed over the past two years, and we have also seen indiscriminate attacks against civilians and the targeting of health-care personnel and aid workers," said Robert Mardini, head of ICRC operations for the Near and Middle East.
Meanwhile, European Union governments rejected a Franco-British push on Friday to lift an EU arms embargo to allow weapons supplies to Syrian rebels, voicing fears this could spark an arms race and worsen regional instability.
France and Britain found little support for their proposal to ease the embargo at an EU summit in Brussels, EU diplomats said, although they asked the bloc's foreign ministers to look again at the issue next week.
"Nobody really is interested (in lifting the embargo)," an EU diplomat said. "There is no prospect of change any time soon."
EU governments want to support the rebels, but many expressed fears on Friday that allowing weapons to flow to them could lead to arms falling into the wrong hands -- especially Islamist militants in the rebel ranks -- and lead Assad's backers to step up arms deliveries to his government.
European Council President Herman van Rompuy said leaders had asked their foreign ministers to look at the issue "as a matter of priority" at a March 22-23 meeting in Dublin.