The country's foreign minister told the UN chief that humanitarian aid won't be allowed even as rebel forces clash with the Lebanese Hezbollah.

Syria’s State-run news agency said the country’s foreign minister has told U.N. chief Ban Ki-moon that humanitarian aid won’t be allowed into an embattled rebel-held Syrian town until the fighting there is over.

The SANA news agency said Mr. Ban called Foreign Minister Walid al-Moallem on Sunday to express concern over the situation in the town of Qusair. On Saturday, the International Committee of the Red Cross and U.N. humanitarian agencies called for a cease-fire, expressing alarm over the fate of thousands of civilians believed to be trapped there, including many wounded.

Mr. al-Moallem told Mr. Ban the Red Cross and others will be able to enter Qusair “after the end of military operations there”.

The regime launched an offensive against Qusair three weeks ago and has gained ground, though rebels have defended some positions.

Meanwhile, Syrian rebels fought with gunmen from Lebanon’s Hezbollah militia in a deadly clash on Lebanese soil overnight, a security official and local media said, in the latest sign that Syria’s civil war is spilling over the country’s borders.

In the night from Saturday to Sunday, Hezbollah apparently encircled and ambushed a group of Syrian rebels and allied Lebanese fighters whom they suspected of rocketing Baalbek a day earlier, said the Lebanese security official.

The Lebanese TV station Al-Mayadeen, seen as sympathetic to the Syrian regime, quoted Lebanese security officials as saying 17 fighters from Jabhat al-Nusra, a rebel group linked to the global al-Qaeda terror network, were killed in the fighting.

It was the worst clash on Lebanese territory since the outbreak of the conflict more than two years ago.

Rebel fighters have threatened to attack Hezbollah bases in Lebanon, and on Saturday 18 rockets and mortar rounds hit Lebanon’s eastern Baalbek region, a Hezbollah stronghold.

The growing tensions between Hezbollah and rebels trying to oust Assad are linked to a regime offensive against the rebel-held town of Qusair in western Syria. Hezbollah’s involvement in the battle for control of the strategic town has exposed its growing role in the Syria conflict, prompting rebel threats to target Hezbollah’s bases in Lebanon.

Meanwhile, low-flying Israeli warplanes again violated Lebanese airspace, overflying the capital Beirut, the eastern Bekaa Valley and the city of Baalbek, Lebanese security officials and the state-run news agency said.

Israeli warplanes regularly enter Lebanese airspace. A security official confirmed the Sunday over-flights and said they were among the most intense recently.

There was no immediate comment from Israel. The flights come amid heightened regional tensions because of the civil war in Syria. Israel is believed to have carried out three airstrikes inside Syria this year said to be aimed at weapons meant for Hezbollah.

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