Battle imminent in Aleppo

The head of world-wide UN peacekeeping missions, Herve Ladsous, referring to Assad's forces, said that the "focus is now on Aleppo, where there has been a considerable build-up of military means."

A commander of the rebel Free Syria Army, Abu Omar al-Halabi told the German news agency DPA by phone that "dozens of trucks loaded with troops and backed by more than 100 tanks are being positioned around Aleppo.

Rebels have held out for days in opposition zones within Syria's main commercial center, mainly in eastern and southwestern districts, during bombardments.

Gigantic outflow feared

The UN's refugee commissioner Antonio Guterres added to UN alarm one day after former UN chief Kofi Annan said he was quitting as Syria crisis mediator, by warning of a "gigantic outflow" of people if the fighting in Syria escalates further.

"We all have seen crisis of this nature in different parts of the world, let's hope that this doesn't evolve into the kind of gigantic outflows we have witnessed in Afghanistan or Iraq," said Guteres in Geneva.

The UN estimates that 1.5 million people have already been displaced within Syria by fighting that began 17 months ago.

Mortars strike refugee camp

In Damascus, forces loyal to Assad moved in on remaining opposition enclaves, a day after mortars struck a local Palestinian refugee camp, killing at least 20 people, including two children.

The Syrian Observatory for Human Rights said the camp, Yarmuk, on the capital's southern outskirts had taken in residents of an adjacent neighborhood Tadamon during two days of clashes between government forces and opposition fighters.

Palestinian president Mahmud Abbas condemned what he called a "heinous" attack, saying the dead and wounded were "unarmed civilians."

Annan appeals to Russia, China

Annan, who ends his mission late August, said on Friday that the "stalemate" within the UN Security Council over Syria could still be overcome.

Writing in the Financial Times, Annan urged two veto-powers, Russia and China, and Iran to make "concerted efforts to persuade Syria's leadership to change course and embrace a political transition."

The text of an Arab-backed resolution being debated at the UN General Assembly condemns the continued and widespread violence in Syria, "irrespective of where it comes from, including the series of bombings which are indicative of the presence of well-organised terrorist groups."

UN chief Ban Ki-moon urged the major powers to "again find common ground."

"The immediate interests of the Syrian people must be paramount over any larger rivalries of influence," Ban said.

"The acts of brutality that are being reported may constituted crimes against humanity or war crimes," he added.

The resolution also demands that Syrian authorities "strictly observe" obligations under international law not to use, transfer or produce chemical and biological weapons.

Manoeuvres off Syria

Russian news agencies, meanwhile, say three Russian naval ships carrying marines will dock in the next few days at Tartus, a Syrian port leased by Moscow.

Two days ago two US media outlets, NBC and CNN, said President Barack Obama had signed a covert document, allowing the CIA and other agencies to provide clandestine support for rebels in Syria.

ipj/ng (Reuters, AFP, dpa)