Syrian government forces killed at least 16 people and wounded some 340 on Tuesday when they unleashed a heavy artillery barrage on a rebel-held district of the city of Homs, activists said.

The bombardment rained down as International Committee of the Red Cross officials tried to negotiate a halt to the fighting to allow them to bring aid to civilians suffering in horrendous conditions after 18 days of attacks on Homs.

In Damascus, security forces opened fire on demonstrators overnight, wounding at least four, activists said, in the latest sign that the 11-month uprising against President Bashar al-Assad was taking a grip on the capital as well as the provinces.

Western powers and the Arab League prepared for a meeting of the “Friends of Syria” contact group in Tunisia on Friday to pressure Assad to step down, while Russia and China backed Assad’s own program for reforms.

Activists said the government forces launched the artillery attack on Homs after rebel fighters holding the opposition Baba Amro district blocked troops from entering.
The London-based Syrian Network for Human Rights said at least 250 shells and rockets had hit Baba Amro since the morning.

The government forces backed by armor and under the control of Alawite officers, from the same minority sect as Assad, have been advancing on Baba Amro, a Muslim Sunni neighbourhood, since the offensive on Homs began on February 3.

Elsewhere, an activist group in Kfar Tkharim near the Turkish border said rebel fighters had killed five soldiers and captured two in an ambush on a government column.