Beirut ? Medics stitch wounds with thread used for clothing. Hungry residents risk Syrian government sniper fire or shelling to hunt for dwindling supplies of bread and canned food on the streets of the besieged city of Homs.

The opposition stronghold was being destroyed “inch by inch,” by government forces, with collapsed walls and scorched buildings, according to accounts Thursday, while Western and Arab leaders hoped to silence the guns long enough to rush in relief aid.

The pressure for “humanitarian corridors” into the central Syrian city of Homs and other places caught in President Bashar Assad’s crushing attacks appeared to be part of shifts toward more aggressive steps against his regime after nearly a year of bloodshed and thousands of deaths in an anti-government uprising.

In back-to-back announcements, U.N.-appointed investigators in Geneva said a list for possible crimes against humanity prosecution reaches as high as Assad, and international envoys in London — including U.S. Secretary of State Hillary Rodham Clinton — made final touches to an expected demand for Assad to call a cease-fire within days to permit emergency shipments of food and medicine.

Washington and European allies remain publicly opposed to direct military intervention. But there have been growing signs that Western leaders could back efforts to open channels for supplies and weapons to the Syrian opposition, which includes breakaway soldiers from Assad’s military.

In a sign of the international divide, however, key Assad ally Russia said Moscow and Beijing remain opposed to any foreign interference in Syria. Russian President Dmitry Medvedev spoke by telephone with the president of the United Arab Emirates and emphasized that “foreign interference, attempts to assess the legitimacy of the leadership of a state from the outside, run counter to the norms of international law and are fraught with the threat of regional and global destabilization,” the Kremlin said.