United Nations observers have been blocked by Syrian troops from the site of a new mass killing, the head of the monitoring team said today.

Shells slammed into the central Syrian city of Homs today, killing more than two dozen people, activists said, as Syria’s government defied ceasefire demands and international efforts to boost the rebels.

Syria’s president defied international pressure to end the year-old crackdown on an uprising against him and said yesterday he was determined to go on fighting what he called “foreign-backed terrorism”.

Syrian troops have shelled a southern village and clashed with army defectors holed up inside in violence that killed a 15-year-old boy and five government soldiers, activists said.

Clashes between Syrian troops and army defectors in the country’s north west killed four people today, while gunmen shot dead a political activist in the latest in a wave of targeted killings in a rebellious central city, activists said.

Syrian troops have targeted forces opposed to President Bashar Assad in clashes that have left seven soldiers and policemen dead, a military official said.

Syrian forces attacked a central town and stormed parts of an eastern city, killing at least four people in fresh fighting as President Bashar Assad’s government struggled to crush a five-month-old uprising, activists said.

Syrian troops bombarded a town in the central province of Homs with artillery today, causing several casualties a day after nine people were killed in a continuing crackdown in the country’s turbulent heartland, activists said.

Syria’s president has granted citizenship to thousands of Kurds living in a north-eastern province as part of overtures to ease the pressure of widespread anti-government protests.