DAMASCUS: Rebels have heightened their offensive in northern Syria, attacking Aleppo airport and two airbases, as the UN rights chief urged international action against President Bashar al-Assad.

Regime troops on Saturday fended off fierce rebel onslaughts around Aleppo international airport and the adjacent Nayrab military airbase, the Syrian Observatory for Human Rights said.

East of Aleppo, rebel attacks around the Kwiyres military airbase sparked counter-strikes from regime warplanes.

The insurgents launched the “Battle of the airports” on February 12, and they have since seized Al-Jarrah military airport and a military complex tasked with securing Aleppo's civilian airport.

Rebels on Saturday also overran a military police checkpoint in the Golan Heights town of Khan Arnabeh just beyond the outer ceasefire line along the demilitarised zone bordering Israel, the Observatory said.

Regime forces responded by shelling Khan Arnabeh and the nearby village of Jubata al-Khashab, inside the ceasefire zone, forcing a rebel retreat.

The Israeli military said it had taken seven Syrians wounded in clashes on the Golan to a hospital inside the Jewish state, revising an earlier number of five.

The Golan has been tense since the near two-year Syrian uprising morphed into a bloody insurgency, at times spilling over with mortar and gunfire into the Israeli-held zone but with serious escalation so far contained.

Northwestern Syria has meanwhile fallen into a security vacuum, illustrated by reports on Saturday that more than 300 people were abducted in tit-for-tat kidnappings in 48 hours, the Britain-based Observatory and residents said.

The spate of abductions, involving large numbers of women and children, began on Thursday when upwards of 40 civilians from Shia-majority villages were kidnapped by armed groups in Idlib province.

Hours later, more than 70 people from Sunni areas were seized in retaliation by gunmen from nearby Shia villages. Subsequently, dozens more people from mostly Sunni opposition towns were captured.

UN rights chief Navi Pillay on Saturday said the international community was hesitating to take action on Syria, weighing up whether any military intervention would be worth it.

Urging that some sort of international action be taken against Syrian President Bashar al-Assad, Pillay repeated her call for him to be investigated for “crimes against humanity and war crimes”.

Asked by Britain's Channel 4 television whether it would be difficult for the United Nations to intervene in a place like Syria, she said: “It's an intergovernmental decision on what kind of action: intervention, peacekeeping, military intervention or a referral to the international criminal courts.

“We urge that action be taken immediately. If there is doubt or hesitation it is because people are assessing the value of military intervention in places like Libya, Syria and Afghanistan.

“It could become a long, drawn out war with no guarantees that civilians would not be harmed in that process.”

French Foreign Minister Jean-Yves Le Drian at a security forum in Abu Dhabi called for urgent action to bring about a power transfer that excludes Assad. Le Drian said the change should be “a transition in which President Assad would no longer keep his place,” and accused Assad and his family “of clinging to power by multiplying the daily massacres and atrocities.”

The remarks came after the umbrella opposition National Coalition on Friday refused to accept Assad in any talks on ending the 23-month conflict, as part of a “framework” it has drawn up for a political solution.

Most of the rebels fighting the Damascus regime are Sunni, while the ruling clan and many of its most fervent supporters are members of the minority Alawite sect, an offshoot of Shia Islam.

Kidnappings driven by a hunger for ransom but often tinged with sectarianism have multiplied in Syria during the revolt that the United Nations says has killed almost 70,000 people.

At least 84 people,including 31 soldiers, 30 rebels and 23 civilians, were killed in violence across the country on Saturday, according to the Observatory.

The leader of the Shia militant group Hezbollah, meanwhile, said on Saturday that while Syria may be weakened by its bloody conflict and unable to fight against Israel, his organisation was capable of defending Lebanon.

“We have everything we need in Lebanon. We don't need to transport (arms) from Syria or Iran.”