Some 350 Syrian dissidents convened in Istanbul on Saturday to discuss strategies to oust Bashar Al-Assad\'s regime as a simultaneous gathering in Damascus was cancelled after deadly protests. The Syrian security forces \"attacked yesterday, killed 19 persons, hundreds of people were sent to hospital, and they arrested some people and they would not allow anybody to hold any meeting,\" Haitham al-Maleh, a senior opposition activist told AFP in Istanbul. Syrian activists said Friday that at least 28 civilians were killed, including 16 in Damascus, in a clampdown on the largest anti-regime rallies in four months that saw more than one million people take to the streets in just two cities -- Hama and Deir Ezzor. The gathering in Istanbul -- titled the National Salvation Congress -- kicked off in a packed conference hall, decorated with Syrian flags, after a minute of prayer and the Syrian national anthem. \"The Congress is expected to endorse a roadmap aiming to take the country from the state of totalitarianism and tyranny towards democracy, and to set response mechanisms to the clear demand of the Syrian street, that is to overthrow the regime,\" the organisers said in a statement. Participants came from various countries and belonged to many different opposition groups, according to organisers. They were expected to also set up a permanent structure to coordinate the opposition. \"We have a paper with our view for the future, for changes in Syria, for democracy and freedom,\" said Maleh, a 79-year-old lawyer and human rights campaigner. \"We will see if anyone has any (objections) to our paper, we will make corrections possibly and then we will elect a group of maybe 15 people to continue working outside Syria. We will connect those inside and outside Syria,\" he said. Maleh voiced optimism that the ouster of Assad\'s regime could be imminent. \"Democracy is coming... God willing, this regime will fall within weeks,\" he said. Syrian opposition groups have held two other meetings in Turkey since anti-regime demonstrations began in March, as thousands of Syrians fled to Turkey to escape bloodshed. Ankara, whose ties with Damascus have flourished in recent years, has piled up pressure on Assad to initiate reform but has stopped short of calling for his departure. But Turkey\'s frustration with his foot-dragging on reform has grown. Last month, Prime Minister Recep Tayyip Erdogan accused Damascus of perpetrating an \"atrocity\" against demonstrators, the harshest remark yet in Ankara\'s criticism of the security crackdowns, which activists say, have claimed the lives of more than 1,400 civilians.