Syria denied reports on Saturday that President Bashar al-Assad's deputy had defected and his forces pressed an offensive against rebels, bombarding parts of Aleppo in the north and hitting 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 issued 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 turned into a civil war, has suffered a string of defections including 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 first erupted against Assad, from the minority Alawite sect which is an offshoot of Shi'ite Islam.
The 73-year-old former foreign minister kept a low profile as the rebellion escalated 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 political solution to end the bloodshed and welcomed the appointment of veteran Algerian diplomat Lakhdar Brahimi as a new international mediator for Syria.
Brahimi, who hesitated for days to accept a job that France's U.N. envoy Gerard Araud called an "impossible mission," will replace former U.N. Secretary-General Kofi Annan, who is stepping down at the end of the month.
Annan's six-point plan to end the violence and move 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 turned increasingly to air power to hold back lightly armed rebels in the capital Damascus and Aleppo, a northern commercial hub. More than 18,000 people have died and some 170,000 have fled the country as a result of the fighting, according to the United Nations.
The Syrian Observatory for Human Rights said the army bombarded neighbourhoods 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.
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.
In the town of Tel, north of Damascus, local activists said the bodies of 40 people killed in bombardment were gathered together for a joint burial. A picture showed what appeared to be several corpses wrapped in colorful blankets on a street.
U.N. MONITORS LEAVING
The last U.N. observers who deployed in Syria four months ago to monitor Annan's failed ceasefire will leave after midnight on Sunday, when their mandate expires.
They will leave a "liaison office" open in Damascus after their departure, though its size and role have not been finalized, a U.N. spokeswoman said.
"The comfort for me is that the U.N. will stay in the country," General Babacar Gaye, head of the departing U.N. Supervision Mission in Syria, told reporters in Damascus.
"The United Nations is committed to ending violence, committed to triggering dialogue between the parties."
Brahimi, a Nobel Peace laureate, will have a new title, Joint Special Representative for Syria. Diplomats said the change was to distance him from Annan, who had complained that his Syria peace plan was hampered by a divided Security Council.
In an interview with France 24 television, Brahimi said he would soon meet with the Security Council.
"We are going to discuss very seriously how they can help," he said. "They are asking me to do this job. If they don't support me, there is no job. They are divided, but surely they can unite on something like this and I hope they will."
Humanitarian conditions in Syria have deteriorated as fighting worsens, cutting off civilians from food supplies, health care and other assistance, U.N. agencies say. Sewage-contaminated water has led to a diarrhoea outbreak in the countryside around Damascus, with 103 suspected cases.
Some 1.2 million people are uprooted in Syria, many staying in schools or other public buildings, U.N. officials say. U.N. humanitarian chief Valerie Amos, ending a visit to Syria, said on Thursday up to 2.5 million people needed aid there.