"This is the largest prisoner exchange to date," Sonmez said. "We are pleased that people from all sides who were held and victimized have finally been freed."
"Turkey and Qatar, who have influence over the rebels, spoke with the rebels. They also spoke with Iran. Iran for its part spoke with Syria."
Turkey's state-run agency Anadolu Agency also said a group of people, including women and children, held in the Syrian Interior Ministry building in Damascus had been released and were escorted onto buses. The report could not be confirmed because of government restrictions on journalists in Syria.
Bulent Yildirim, the head of the Turkish aid organization, told Anadolu in Damascus that 1,000 people have been released so far, including 74 women and a number of children between the ages of 13 and 15.
Some photographs released from the aid organization showed a group of women lined up against a wall, apparently waiting to be released. Most seemed to be hiding their faces from the camera. Another showed a group of men, their heads shaven, standing in a room.
Regime forces and rebels have exchanged prisoners before, most arranged by mediators in the suburbs of Damascus and in northern Syria, but the numbers ranged from two to 20 prisoners. The Syrian Red Crescent also has arranged exchanges of bodies from both sides.
Nadim Houry, deputy Middle East director for the New York-based Human Rights Watch, said "tens of thousands" of Syrian activists, opposition supporters and members of their families remain jailed in Syria since the uprising began in March 2011.
Many of those in government custody have had no contact with the outside world for months and no access to a lawyer. Most are being held by the state security services around the country, Houry said.
"For every person released, thousands remain detained and thousands more cannot be accounted for," he Told the Associated Press.
The rebels are also known to be holding a group of nine Lebanese Shiites, at least two Iranian engineers and scores of pro-regime supporters and captured soldiers.
Russia's Foreign Ministry said senior Russian and U.S. diplomats will discuss the Syrian crisis in talks later this week with Brahimi.
In a speech Sunday, a defiant Assad ignored international demands to step down and said he is ready to talk — but only with those "who have not betrayed Syria."
He outlined his vision for a peace initiative that would keep him in power to oversee a national reconciliation conference, elections and a new government. But he also vowed to continue to fight terrorists — a term the government uses for the rebels.
The opposition rejected his offer, which also drew harsh international criticism.
Russian officials said Assad's proposals should be taken into consideration.
Syria's Information Minister Omran al-Zoubi said countries such as the United States and its Western allies have dismissed the president's initiative "before even having the time to translate it."
Fraser reported from Ankara, Turkey. Associated Press writers Ali Akbar Dareini in Tehran, Matthew Lee in Washington and Barbara Surk and Zeina Karam in Beirut contributed to this story.
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