US Secretary of State Hillary Clinton speaks during a news conference at the "Friends of Syria" conference in Istanbul April 1, 2012. [Photo/Xinhua]

ISTANBUL - Representatives from more than 80 countries voiced support to the Syrian opposition as they met here Sunday seeking to mount international pressure on Syrian President Bashar al-Assad's government to stop the year-long violence and agree on a peaceful political transition.

After the Second Conference of the Group of Friends of the Syrian People in Istanbul Convention Center, the participants reaffirmed in a statement their determination to support "the just cause of the Syrian people" to oppose Assad's regime.

The meeting agreed to recognize the opposition Syrian National Council (SNC) as a legitimate representative of all Syrians and an umbrella organization for Syrian opposition groups, noting the council as the leading interlocutor of the Syrian opposition with the international community, said the statement.

The statement criticized the Syrian government's "widespread and systematic violations of human rights and fundamental freedoms."

It also urged the UN-Arab League joint envoy for Syria, Kofi Annan, to come up with a timetable to determine his next steps, including returning the Syrian issue to the UN Security Council if the Syrian government fails to end the violence.

US Secretary of State Hillary Clinton said at a press conference shortly after the conference that "Assad must go," demanding Assad's forces halt operations targeting civilians or face "serious consequences."

She said that the United Nations' effort to broker an end to the violence is faltering as Assad ignores his pledge to abide by a peace plan proposed by Annan.

Turkish Prime Minister Recep Tayyip Erdogan urged the international community to take a resolute stance to stop bloodshed in Syria, adding that the United Nations and Arab League's resolutions provided a blueprint to end the Syrian crisis.

"The international community should take a committed position on the Syrian crisis. UN and Arab League resolutions offer a clear road map on how to end the crisis," Erdogan said at the conference.

The conference vowed to render all possible assistance, both technical advice and direct support, to a Syria-led political process that is peaceful, orderly and stable. It also agreed to continue and increase, as a matter of urgency, its assistance, including funding and financial support, to meet the needs of the Syrian people.

Washington will offer another $12 million in humanitarian aid for Syria's embattled population, and will also provide communication equipment to help the opposition forces evade government attacks, Clinton said.

A Sanctions Working Group will be formed to achieve greater effectiveness in enforcing the restrictive measures already put in force by the international community, including the measures stipulated by the first meeting of Friends of Syria held in February in Tunisia.

France will chair the first meeting of the working group in April along with other members of the group.