BEIRUT (AP) -- Syrian warplanes struck rebel positions near a besieged military air base and other rebel-held areas in the country's north Tuesday as regime forces stepped up attacks against opposition fighters in the key province of Aleppo, activists said.
Rebels fighting to topple President Bashar Assad have for months been trying to take Kweiras and two other military air bases nearby without success. The government has recently gone on the offensive in the province and in areas in the country's heartland to recapture rebel-held territory.
Activists said warplanes also struck targets in the villages of Atareb and Kfar Hamra in Aleppo province, and troops clashed with rebels inside the provincial capital of the same name. There were no immediate reports of casualties. The regime has gone on the offensive in Homs and Aleppo, the country's largest city, to build on the momentum from its victory at the strategic town of Qusair earlier this month.
The violence also continued to spill over the border. Heavy clashes erupted between pro-Hezbollah gunmen and followers of a radical Sunni cleric in southern Lebanon, killing two people, officials said.
Lebanon has been on the edge for months and bursts of violence between supporters and opponents of Assad have become frequent.
The country is deeply divided along sectarian lines, with Sunni Muslims largely supporting their brethren in Syria, who make up the majority of the rebellion against Assad's regime, and many Shiites supporting Assad, whose regime is dominated by Alawites, an offshoot sect of Shiite Islam.
The polarization has deepened in recent weeks after Hezbollah, a Lebanon-based Shiite militant group backed by Iran, openly joined the fight in Syria on Assad's side and helped his troops crush rebels in the town of Qusair just over the border in Syria earlier this month.
The clashes broke out in an eastern suburb of Sidon erupted Tuesday after several people threw stones and shattered windows in a car belonging to Amjad al-Assir, the brother of Hezbollah critic and hard-line cleric Sheik Ahmad al-Assir, the officials said. A statement from al-Assir's office said he was not driving it at the time. Al-Assir then gave Hezbollah a one week ultimatum to vacate apartments occupied by the group's supporters in the mostly Sunni city as clashes broke out with gunmen wielding automatic rifles and rocket-propelled grenades. Officials believed the gunmen fighting al-Assir's followers to be Hezbollah sympathizers.
Lebanese army troops deployed in the area of the fighting, which subsided after several hours. The military called on gunmen to withdraw immediately from the streets.
Earlier Tuesday, Lebanon's official news agency said gunmen shot and wounded a Syrian man, whom it said was believed to have been involved in a deadly attack on four Shiite youth in Ras Baalbek, a Hezbollah stronghold that is also home to Christians in a volatile area near the border with Syria.
The National News Agency did not elaborate on the suspected connection between the attack on the Syrian in the town of Labwa and the killing of four Shiites in a Sunday ambush nearby.
The Syrian uprising began more than two years ago with peaceful protests against Assad, but later grew into a civil war that has killed 93,000 people and likely many more, according to the U.N.
Millions of Syrian fled their homes and sought shelter in neighboring countries with Jordan and Lebanon hosting the bulk of them, further fueling fears that Syrian conflict's sporadic spill overs across the border into the Arab country of 4 million people will turn into a full blown war.
Lebanon, a country of 4 million which is still recovering from its own 15-year civil war that ended in 1990, is hosting over half a million refugees.
In Syria meanwhile, an explosion inside a housing complex in a rebel-held village in the country's northern Idlib province killed 20 people, the Britain-based Syrian Observatory for Human Rights said.
It was not immediately known what caused the explosion and who was behind it. Nobody claimed responsibility for the blast.
The complex belonged to a member of parliament, the group said. The lawmaker, Ahmed al-Mubarak, was not in the area at the time of the explosion but his brother was among those killed, the Observatory's director Rami Abdul-Rahman said.
Associated Press writers Bassem Mroue and Sarah El Deeb in Beirut contributed to this report.
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