Violence casts doubt on Syria peace plan Syrian forces stormed a Damascus suburb on Sunday, activists said, fuelling doubts about a peace plan the UN Security Council voted the previous day to support with more observers. Shortly before UN and Arab League envoy Kofi Annan called on the Syrian government to honour its commitment to his six point peace plan, including withdrawing military units from population centres, armoured vehicles fired on the rebellious Damascus suburb of Douma, activists said, killing at least two civilians. Four members of the regime's forces were later killed by a bomb attack in Douma, according to the UK-based Syrian Human Rights Observatory. The observatory said 11 people - including one member of the security forces - were killed elsewhere in the country, mostly in the province of Homs in central Syria. Some of the eight UN monitors in the country to monitor a shaky truce brokered by Mr Annan which came in to effect over a week ago visited the central province of Hama on Sunday, a UN official said, whilst two remained stationed in the battle-blasted city of Homs. The observer force is expected to be brought up to 30 in the coming days, and on Saturday, the Security Council authorised the deployment of up to 300 monitors, though many fear even an expanded mission will not be enough to rescue a repeatedly violated ceasefire. Mr Annan urged "all forces whether governmental, opposition or others" to put down their weapons in a statement released on Sunday, but said that the government in particular should stop using heavy weapons and withdraw its armed units from population centres. Over 9,000 people are estimated to have been killed since last March as a brutal crackdown on pro-democracy protests has evolved in to a military campaign to wipe out a lightly armed insurgency. In a sign of the repercussions of the conflict, Tunisian media over the weekend identified six Tunisians who died fighting against President Bashar al-Assad alongside rebels in Syria. Three of the dead hailed from the small hardscrabble southern town of Ben Guerdane, along the Libyan border, according to the independent Tunisian newspaper Assabah. The newspaper, which named the victims and described them as "martyrs" of the Syrian revolution, said they had entered Syria from the Turkish border and died in the provinces of Homs and Idlib, centres of confrontation between Mr Assad's forces and rebels fighting the regime. At least three fighters from near the Libyan city of Misurata earlier this year were reported to have died fighting alongside Syrian rebels. The increasing numbers of reported foreign combat deaths suggest that international outrage over Mr Assad's violence against peaceful protesters has inspired at least some idealistic and pious young Arab men, especially from countries that overthrew dictatorships last year, to join the Syrian fight against the Damascus regime in the same way they fought against the US invasion of Iraq and the Soviet invasion of Afghanistan. Additional reporting by Borzou Daragahi in Cairo