Representatives from more than 70 countries started a conference here on Sunday to explore ways to mount international pressure on Syria's Bashar al-Assad regime to stop year-old violence and agree on a peaceful political transition.

Turkish Prime Minister Recep Tayyip Erdogan and U.S. Secretary of State Hillary Clinton are among those who are attending the Second Conference of the Group of Friends of the Syrian People in Istanbul Convention Center.

However, UN-Arab League Envoy for Syria and former UN chief Kofi Annan and Catherine Ashton, High Representative of the European Union (EU) for Foreign Affairs and Security Policy, did not come for the meeting.

Russia and China, which vetoed a Security Council resolution calling Damascus to end the violence, have said they would not participate in Sunday's conference, while Iran and the countries which voted against a UN General Assembly resolution were not invited to the meeting.

Turkish prime minister made a keynote address at the conference. Heads of delegations will also make statements in the meeting.

Erdogan said the Syrian people are not fighting alone. Turkey supports the Syrian people in their struggle for freedom.

However, he said, Turkey does not want to interfere the domestic affairs of any country and pursue any interest. But Turkey will struggle and safeguard freedom in the region.

"The problem in Syria does not only affect Syria but it affects the region and the world," he said.

He urged the international community to speak one voice and act one action in order to end the bloodshed in Syria.

"New Syria will be decided by Syrians, and Syrians only," he added.

Qatari Prime Minister and Foreign Minister Sheikh Hamad bin Jassim bin Jabor Al Thani said at the meeting that it is unacceptable for the Syrian regime to kill its own citizens and buy any time while voicing his support to efforts by UN-Arab League Envoy for Syria and former UN chief Kofi Annan.

He said that the international community should increase pressure on the Assad regime to stop the killing in the country.

Nabil El Arabi, Secretary-General of the League of Arab States, said that this meeting has three targets, to have a joint voice to support the Syrian people, seek ceacefire to stop bloodshed, and support Syrian opposition the Syrian National Council.

However, he stressed, "regional powers should join together to support the Syrian people in their struggle" and "the future of Syria should be fully determined by Syrian people."

Addressing delegates at the meeting, Syrian opposition group Syrian National Council's chairman Burhan Ghalioun called on the international community to take responsibility and do not allow the Syrian regime to feel at ease and buy time, adding that the Syrian regime poses threat to the Arab world as a whole.

He said that the Syrian people will fight for a free Syria and the Syrian regime will fall.

The Istanbul meeting follows a first "Friends of Syria" conference in Tunis on February 24 which was attended by leading officials from Western and Arab countries.

This meeting comes in the wake of a gathering of representatives of 25 Syrian groups opposing Assad's rule, held in Istanbul on March 27-28, which produced a "national covenant" outlining the opposition's vision for a democratic future for Syria. Not everyone was on board as Syrian Kurdish groups walked out of the meeting.

The meeting is expected to bolster the standing of the Syrian opposition while participants are discussing whether they will raise status of the Syrian National Council as principal representative of the Syrian people.

Other topics on the agenda will be fresh sanctions against Damascus, buffer zone inside Syria and ways to deliver humanitarian aid.

On the occasion of the meeting, Turkey renews a call for international help to deal with ever growing numbers of Syrians fleeing violence to Turkey's southern provinces, the figure now having reached 18,000.