July 28 (Bloomberg) -- Syrian troops loyal to President Bashar al-Assad clashed with rebels in Aleppo as the former head of the United Nations’ observer mission said Assad’s fall is “just a matter of time.”

Major General Robert Mood, the Norwegian who commanded the UN monitoring mission for three months, told a news conference in Oslo yesterday that “it’s impossible to imagine a future in Syria where the current people remain in power,” the Associated Press reported.

Still, he said, the Assad regime has the military resources to sustain its fight for months or even years, and a collapse of the regime “could easily be the start of a situation that is way worse” than the current level of bloodshed.

Aleppo, Syria’s most populous city, is shaping up as the biggest test yet of opposition fighters’ capabilities against the regime’s artillery and air power, with thousands of civilians fleeing the area to avoid what the U.S. warns may be a “massacre.” The city is Syria’s commercial capital with a population the U.S. Central Intelligence Agency estimates at 3 million.

“I am deeply concerned by reports that the Syrian government is amassing its troops and tanks around Aleppo and has already begun a vicious assault on the city and its civilian population,” U.K. Foreign Secretary William Hague said in an e- mailed statement yesterday. “This utterly unacceptable escalation of the conflict could lead to a devastating loss of civilian life and a humanitarian disaster.”

‘Suffering Civilians’

The U.S. has “grave concerns” about Assad’s actions, State Department spokeswoman Victoria Nuland said July 26 in Washington. The U.S. is alarmed that “we will see a massacre in Aleppo, and that’s what the regime appears to be lining up for,” she said.

UN Secretary-General Ban Ki-moon, in London for the opening of the Olympic Games, yesterday appealed to the Syrian government to halt its offensive.

“The violence from both sides must stop for the sake of the suffering civilians,” he said, as he has before without effect in recent months.

Opposition groups also reported fighting in the northern province of Idlib, Daraa to the south and the suburbs of Damascus, the capital, where the government used helicopter gunships to blast rebel hideouts, according to the Syrian Observatory for Human Rights. Protests against Assad erupted in Homs, Hama and other provinces after Friday prayers, Al Arabiya television reported.

Chemical Weapons

At the UN in New York, the Arab League circulated a draft resolution for the 193-member General Assembly calling on Secretary General Ban Ki-moon to arrange for “prompt investigations” of Syria’s stockpile of chemical weapons. The League also demanded that Assad secure the arsenal amid reports of movement of such weapons.

The largely symbolic resolution is meant to show the scale of international opinion since such assembly measures are only binding if approved by the Security Council, where Russia and China have protected Syria with their veto power. A vote is expected Aug. 1.

International and regional efforts have failed to end the violence in Syria, which began in March 2011 and has left at least 19,000 people dead, including about 5,000 government troops, according to the Observatory. As many as 200 people were killed July 26, including 48 in Aleppo and 46 in Damascus, the opposition Local Coordination Committees in Syria said on its website.

Syrian state media said the army killed four “terrorists” after prayers in Daraa, and authorities dismantled eight bombs near a mosque in the Damascus suburb of Hajar al-Aswad.

‘Extremely Volatile’

The International Committee of the Red Cross is moving some of its foreign staff out of Damascus to Beirut in neighboring Lebanon due to “security conditions,” spokeswoman Carla Haddad Mardini said yesterday by phone from Geneva. A 50-member team, including 11 expatriates, will remain in the city, she said.

“The situation in Aleppo is extremely volatile and in Damascus, too, thousands of people have fled their homes in search of safety,” the Red Cross said in a statement.

U.S. Ambassador to Syria Robert Ford stressed in a statement to the Syrian people yesterday the need for individual accountability for crimes being committed in the country and the importance of justice rather than retribution in a post-Assad era.

“Neither a community nor an ethnicity must be blamed for the actions of individuals in the regime,” he wrote on the U.S. embassy’s Facebook page. “It must be clear that only individuals who committed crimes against humanity will be identified and held accountable for their abhorrent actions.”

Internationally backed initiatives, such as the Syrian Justice and Accountability Center, will “coordinate efforts to research and collect evidence of human-rights violations for use in future Syria-led transitional justice processes,” according to Ford.

--With assistance from Nadeem Hamid and Nicole Gaouette in Washington, Flavia Krause-Jackson in United Nations and Eddie Buckle in London. Editors: Terry Atlas, Michael Shepard