"There was bombing on Syrian territory, not Lebanese territory," the spokesman said.

Earlier, inhabitants of Arsal, a border region in Lebanon's Bekaa Valley, told AFP they saw Syrian planes flying over the area at dawn.

Syrian rebels and their sympathisers often carry out operations inside Syria before crossing back over the porous and sometimes undefined border into Lebanon.

Moreover, shelling from Syria into Lebanon and cross-border shootings have become near-daily occurrences in recent months.

Lebanese officials have protested only twice to Damascus, whose troops withdrew from Lebanon in 2005 after three decades of occupation.

More than 150,000 Syrians are said to have fled to Lebanon where factions for and against Syrian President Bashar al-Assad's regime are deeply divided.

General Martin Dempsey's visit is part of an "operational planning" mechanism established between Turkey and the United States to prepare for the aftermath of Syrian President Bashar al-Assad's embattled regime.

Dempsey, chairman of the Joint Chiefs of Staff, met with senior Turkish officials, including his counterpart Necdet Ozelwas.

Apart from Syria, he was also expected to discuss a range of other issues during his visit including counter-terrorism and Iran's nuclear programme.

Turkey has floated the idea of a "safe zone" to protect refugees fleeing the violence in Syria but that would require foreign military protection, an idea Washington has rejected.

"The United States is currently not involved in this issue," Prime Minister Recep Tayyip Erdogan was quoted as saying on Monday in Turkish media, as he criticised the Americans for not fulfilling "what is expected of them."

"Countries that are rather active are Russia and China," he said.

The death toll from the 18-month-old Syrian conflict has risen to more than 27,000 people, according to a tally by activists.

More than 250,000 Syrians have fled the violence to neighbouring countries.

Turkey currently hosts some 80,000 refugees in several camps in the southeast bordering Syria. But it has warned it can handle no more than 100,000 refugees.