Hizbullah
HizbullahIsrael news photo: Flash 90

A commander of the Free Syrian Army (FSA) said on Thursday that Syrian rebels had started to attack the Lebanon-based Hizbullah terror group, the Turkish Anatolia news agency reports.

The attack comes less than a day after the FSA chief of staff issued a 48-hour ultimatum warning Hizbullah to stop shelling territory held by the rebels.

"We have bombed the territories of Hizbullah in Lebanon and Syria. The Free Syrian Army will continue bombing these positions," Col. Hisam al-Avvak of the Group of Free Officers, which operates under the umbrella of the FSA, told Anatolia news agency.

Al-Avvak also threatened that the FSA would target Hizbullah strongholds in the south of Beirut unless the group stops its joint operations with the Syrian army forces.

Gen. Selim Idriss, the FSA chief of staff, said on Wednesday that Hizbullah had long been taking part in hostilities in Syria, but had gone too far by shelling villages near Qusayr in Homs province from the Bekaa valley in Lebanon.

The commander said the rebels were giving the terror group a 48-hour deadline to stop the attacks and "as soon as the ultimatum ends, we will start responding to the sources of fire." Rebels in the Qusayr area would be backed by FSA fighters "equipped with long-range weapons from other areas," he said.

The FSA had also asked the Lebanese president and premier to intervene, Idriss said, but the office of Prime Minister Najib Mikati denied any contact with the Syrian rebels.

Hizbullah has repeatedly denied sending fighters into Syria. Its leader, Hassan Nasrallah, acknowledged in October 2012 that Hizbullah members had fought Syrian rebels but said they were acting as individuals and not under the group's direction.