At the meeting in Cairo, organized by the Arab League, Turkey and Arab states urged the Syrian opposition to unite and form a credible alternative to the government of President Bashar al-Assad.
The conference was attended by some 200 Syrian opposition figures but was boycotted by the Free Syrian Army, which is leading the armed struggle against Assad's forces.
The armed Syrian rebels oppose a plan drafted by world powers last weekend for a political transition in Syria that could include current regime members.
The Cairo conference suffered a further setback on July 3 when the Syrian Revolution General Commission pulled out of the talks, citing political "disputes."
The meeting was held as Human Rights Watch released a report detailing systematic ill-treatment and torture of civilians by Syrian government forces.
The New York-based rights watchdog said torture in Syria constituted a crime against humanity and should be prosecuted by the International Criminal Court.
"The Syrian authorities are running a network of torture centers, a network of torture chambers, scattered across Syria," Ole Solvang, a researcher at Human Rights Watch, said.
"And the widespread and systematic nature of this network makes it clear that it constitutes a crime against humanity."
Human Rights Watch's report echoed remarks by Navi Pillay, the United Nations high commissioner for human rights, who on July 3 renewed calls for the International Criminal Court to investigate alleged atrocities in Syria.
Pillay, speaking in New York after briefing the United Nations Security Council, said: "In my view, both government forces and armed opponents have been involved in actions harming civilians. Those responsible for attacks against civilians must be held accountable."
Pillay said the Syrian Army was carrying out "serious" new rights violations, including rape and attacks on hospitals, while opposition forces routinely executed suspected government collaborators.
She also denounced the flow of weapons to Syria, warning against "further militarization" of the conflict.
Pillay did not specify where the weapons were coming from, though Russia and Iran are the government's main suppliers.
Qatar and Saudi Arabia are believed to have been shipping arms to the opposition. The United States has said it is supplying only "nonlethal" aid to the Syrian rebels.
Violence Continues Unabated
The violence in Syria continued to claim lives this week, with the army continuing its bombardment of rebel neighborhoods of the central city of Homs
The Syrian Observatory for Human Rights said at least 30 people were killed across the country on July 2.
The group puts at more than 16,500 the number of people killed in violence since the uprising against Assad's rule broke out in March last year.
Assad's regime has also come under fire for shooting down a Turkish jet last month, sparking Ankara's fury.
In an interview with the Turkish newspaper "Cumhuriyet" published on July 3, Assad said Syrian forces learned that the surveillance aircraft belonged to Turkey only after it was shot down on June 22.
He told "Cumhuriyet" he regretted the incident "100 percent."
NATO member Turkey has responded to the incident by boosting its forces on the Syrian border and warning it will take military action against any incursion by Syria's military.
Thousands of refugees have fled the Syrian conflict to Turkey, and Ankara has repeatedly called for Assad to step down.
Based on reporting by Reuters, AP, and AFP