BEIRUT (Reuters) - Three people were killed in a crackdown on dissent against the rule of President Bashar al-Assad on Saturday, activists said, despite a deadline by the Arab League for Damascus to take steps to end the bloodshed. The Arab League, a powerful political group of Arab states, set the Saturday deadline for Syria to comply with a peace plan, entailing a military pullout from around restive areas, and threatened sanctions if Assad failed to halt the violence. But on Saturday, the Syrian Observatory for Human Rights said two army defectors had been killed in clashes with the Syrian army in Homs, which has become a focus for the uprising against more than 40 years of Assad family rule. One civilian was also killed in a Saturday morning raid by security forces in Hama, another centre for the uprising, the observatory said. Activists said the deaths added to a growing toll from late on Friday, when 25 civilians were killed in attacks by Syrian forces and by gunmen suspected of belonging to the opposition. Ten soldiers were also killed in clashes with army defectors. The United Nations says the crackdown on the protests has killed at least 3,500 people since March. Authorities blame the violence on foreign-backed armed groups which it says have killed some 1,100 soldiers and police. Syria has barred most independent journalists from entering the country, making it difficult to verify reports from activists or officials. Syria has come under growing international pressure to end the crackdown on the eight month revolt. The Arab League suspended Syria's membership over its inability to stem the violence in a surprise move last week. The organisation did not detail what would happen if violence continued up to the deadline, but has threatened political and economic sanctions. On Friday, US Secretary of State Hillary Clinton expressed concern that Syria, seen as a fault line of several regional conflicts, could slide into civil war. "I think there could be a civil war with a very determined and well-armed and eventually well-financed opposition that is, if not directed by, certainly influenced by defectors from the army," she told NBC news in Indonesia, where she was attending a regional summit. Clinton said the international community was reluctant, however, to intervene the same way it did in Libya, where NATO forces backed rebel groups who toppled Muammar Gaddafi. "There is no appetite for that kind of action vis--vis Syria," she said, pointing to moves by the Arab League and Turkey, who have stepped up diplomatic pressure on Syria and threatened to follow the West in implementing sanctions. French Foreign minister Alain Juppe, alongside the Turkish Foreign Minister Ahmed Davutoglu, said France was ready to work with the Syrian opposition and that tougher sanctions were needed. Britain also said it was increasing its contacts with Assad opponents. But Syria's ambassador to Lebanon, Ali Abdulkarim Ali, argued that large pro-government rallies, which have also been organised regularly in recent weeks, showed that foreign pressure would not succeed in weakening the government. "There is great optimism that Syria has the stronger hand and that international pressure will tumble in the face of Syrian national unity and (Syria's) balance and responsible policies that have confronted all these challenges," Ali was cited as saying in the Lebanese daily, al-Safir, on Saturday. Damascus on Friday sought changes to a planned Arab League mission to monitor its implementation of the organisation's plan for ending violence, which Syria argues it has been unable to fully enforce due to armed resistance. The league's secretary general, Nabil Elaraby said the organisation was studying a letter from Syria which "included amendments to the draft protocol regarding the legal status and duties of the monitoring mission." Late night raids by security forces on Friday killed some five residents in Homs and Albukamal, near the Iraqi border. Both towns have seen pro-democracy protests and also play host to armed groups of army defectors. In Homs, which has become a centre of armed uprising but has also seen escalating sectarian violence, gunmen attacked a bus transporting workers and killed at least eleven, an activist told Reuters. "It is likely because some of those workers were Alawites," he said, referring to the minority religious sect to which the Assad family belongs. A resident in Homs, who declined to be named, also told Reuters that defected soldiers attacked a car they said was carrying members of Air Force Intelligence, killing four. The attack comes two days after opposition sources said the Free Syrian Army said it killed or wounded 20 security police in an assault on an Air Force Intelligence complex on the outskirts of Damascus, the first assault of its kind in the uprising.