BEIRUT - Syria denied reports on Saturday that President Bashar al-Assad's deputy had defected and its forces pursued an offensive against rebels, bombarding parts of Aleppo in the north and attacking an insurgent-held town in the oil-producing east. Vice-President Farouq al-Shara "never thought for a moment about leaving the country", said a statement from his office broadcast on state television in response to reports that the veteran Baath Party loyalist had tried to defect to Jordan. Assad, battling a 17-month-old rebellion led by Syria's Sunni Muslim majority that has escalated into civil war, has suffered a string of defections including by his prime minister Riyadh Hijab two weeks ago. Shara, whose cousin - an intelligence officer - announced his own defection on Thursday, is a Sunni Muslim from Deraa province where the revolt began against Assad, a member of the minority Alawite sect that is an offshoot of Shi'ite Islam. The 73-year-old former foreign minister kept a low profile as the rebellion mushroomed but appeared in public last month at a state funeral for three of Assad's top security officials killed in a bomb attack in Damascus. The statement said he had worked since the start of the uprising to find a peaceful, political solution and welcomed the appointment of Algerian diplomat Lakhdar Brahimi as a new international mediator for Syria. Brahimi, who hesitated for days before accepting a job that France's U.N. envoy Gerard Araud called an "impossible mission", will replace former UN Secretary-General Kofi Annan, who is leaving at the end of the month in frustration over jostling among world powers that undermined his peace mandate. Annan's six-point plan to stop the violence and advance towards political negotiations was based on an April ceasefire agreement which never took hold. The conflict has deepened since then with both sides stepping up attacks. Assad's forces have resorted increasingly to air power to hold back lightly armed insurgents in the capital Damascus and Aleppo, a northern commercial hub. More than 18,000 people have died in the bloodshed and about 170,000 have fled the country, according to the United Nations. The Syrian Observatory for Human Rights said the army bombarded neighborhoods in Aleppo, Syria's largest city. Rebels hold several districts in the country's northern commercial hub and have tried to push back an army counter-offensive. State television said soldiers "cleared terrorists and mercenaries" - terms used by authorities to describe Assad's armed opponents - from the western district of Saif al-Dawla, where some of the heaviest fighting has taken place. Internet footage which activists said was filmed in Saif al-Dawla on Saturday showed a plane making a low pass over buildings and dropping two bombs. "They were defeated (in Damascus). They will be defeated very soon in Aleppo," Deputy Foreign Minister Faisal Mekdad told Sky News in Damascus. Mekdad also denied the "absolutely scandalous" reports of Shara's defection. The White House said it had seen reports of Shara's defection but could not confirm them. "At this point, whether or not those reports are true, we have seen in the last several weeks the increasing isolation of the Assad regime," White House spokesman Josh Earnest said to reporters traveling with U.S. President Barack Obama on Air Force One. Brahimi had Washington's support, he added. The Observatory also said at least 20 armored vehicles moved into the eastern town of Mayadeen in Deir al-Zor province, where Syria's 200,000 barrels per day of oil are produced.