DAMASCUS - Rebels on Tuesday overran a military air base and captured warplanes, gaining ground in northern Syria for a second straight day as the UN said the death toll from the 23-month conflict was nearly 70,000.The Syrian Observatory for Human Rights said the rebels captured a military airport at Al-Jarrah in Aleppo province, and in the process seized for the first time a fleet of deployable warplanes including MiG fighter jets. During their assault on the airport, the rebels killed, injured or imprisoned dozens of troops, the watchdog said, adding that as the rest of the troops pulled out, they left behind ammunition and warplanes.Soon afterwards, the air force used fighter jets to bombard the airport to try to dislodge rebels there, the Observatory said, adding warplanes also carried out raids near the international airport which has come under a rebel assault.Speaking to AFP on condition of anonymity, a military source in Aleppo confirmed the rebel capture “after 48 hours of fierce combat”, but downplayed the importance of Al-Jarrah. “It is a very small airport, used for training purposes,” he said. “There are only small amounts of unusable ammunition left there, and several planes that have long been out of action.”Activists meanwhile reported the launch of rebel offensives on the Aleppo international airport and Nayrab military airport nearby, although the military source denied any such assaults. Closed since January 1, “Aleppo’s international airport has in the past suffered attacks, but tightened security measures and the Syrian army’s bravery has stopped armed men from getting anywhere near there,” said the army source. The Observatory also reported a rebel capture of the main road linking Aleppo province to neighbouring Raqa and parts of a military base tasked with securing the area’s airports. Activists in Aleppo have told AFP that fighters in the north have shifted their focus from city battles to the capture of military airports and bases.Assad meanwhile called for “collective action” by the state and Syrian people to limit the effects of the crisis, state news agency SANA reported. The Syrian president also accused “groups that target Syria” of trying to destroy the country’s infrastructure.The conflict has killed nearly 70,000 people since it erupted in March 2011, UN rights chief Navi Pillay said, only a month after putting the toll at 60,000.Pillay also condemned the inaction of the UN Security Council, where China and Russia have used veto powers to block three resolutions that would have threatened sanctions against Assad’s regime.“We will be judged against the tragedy that has unfolded before our eyes. This council, as well of those of us in key positions within the UN, will be rightly asked what we did,” she said. Electricity Minister Imad Khamis said that widespread blackouts have caused economic losses of around $2.2 billion for Syria nearly two years into a spiralling conflict.