Story highlights Alloush blames the obstinacy of the Assad regime and continuing aggression against the Syrian people

There have been repeated violations of a ceasefire since it was announced in February

(CNN) The Syrian opposition's chief peace negotiator, Mohammad Alloush, has resigned over the failure of peace talks to end the country's civil war.

Alloush, who represents the influential Jaish al-Islam rebel group, made his resignation public via Twitter, tweeting that his decision was a result of the failure of the international community to stop the atrocities of Bashar al-Assad's regime against the Syrian people.

Photos: Syrian forces retake Palmyra Photos: Syrian forces retake Palmyra Syrian military engineers detonate mines laid by ISIS militants during an operation to liberate the city of Palmyra, Syria, on Sunday, March 27. Syrian forces recaptured Palmyra from ISIS on Sunday, months after the city fell to the Islamic extremist group, state media reported. Hide Caption 1 of 18 Photos: Syrian forces retake Palmyra A member of the Syrian military walks past a banner bearing ISIS slogans on March 27. Hide Caption 2 of 18 Photos: Syrian forces retake Palmyra Smoke rises near a gas station as a result of fighting between Syrian government forces and ISIS militants on March 27. Hide Caption 3 of 18 Photos: Syrian forces retake Palmyra Damage to the Palmyra Castle, the ancient hilltop citadel formally known as Fakhr-al-Din al-Maani Castle, can be seen following the fighting on March 27. Hide Caption 4 of 18 Photos: Syrian forces retake Palmyra Syrian soldiers carry a wounded comrade after an explosion near the castle on Saturday, March 26. Hide Caption 5 of 18 Photos: Syrian forces retake Palmyra Syrian soldiers climb to the top of the castle to place a flag on March 26. Hide Caption 6 of 18 Photos: Syrian forces retake Palmyra Syrian forces hold a position on the outskirts of Palmyra on March 26. Hide Caption 7 of 18 Photos: Syrian forces retake Palmyra Syrian forces pose next to the Palmyra Castle on March 26. Hide Caption 8 of 18 Photos: Syrian forces retake Palmyra Syrian soldiers stand near the body of an ISIS militant near Palmyra on Friday, March 25. Hide Caption 9 of 18 Photos: Syrian forces retake Palmyra A dust cloud rises near the Palmyra Castle during the military operation to retake Palmyra on March 25. Hide Caption 10 of 18 Photos: Syrian forces retake Palmyra Syrian soldiers survey the damage to a villa belonging to the Qatari royal family on March 25. The villa near Palmyra served as an ISIS headquarters after being abandoned by its owner. Hide Caption 11 of 18 Photos: Syrian forces retake Palmyra Syrian troops hold a position on the outskirts of Palmyra on March 25. Hide Caption 12 of 18 Photos: Syrian forces retake Palmyra Syrian soldiers fire mortars at ISIS positions in Palmyra on March 25. Hide Caption 13 of 18 Photos: Syrian forces retake Palmyra Syrian soldiers reload a cannon near Palmyra on Thursday, March 24. Hide Caption 14 of 18 Photos: Syrian forces retake Palmyra A Syrian soldier takes a position inside a damaged palace at the entrance of Palmyra on March 24. Hide Caption 15 of 18 Photos: Syrian forces retake Palmyra Syrian troops monitor the surrounding area from their location on the outskirts of Palmyra on March 24. Hide Caption 16 of 18 Photos: Syrian forces retake Palmyra Smoke rises near Palmyra during the operation to retake the town on March 24. Hide Caption 17 of 18 Photos: Syrian forces retake Palmyra Syrian troops stand next to a mansion belonging to the Qatari royal family on March 24. Hide Caption 18 of 18

Alloush said the three stages of the Geneva negotiations were not successful because of obstinacy from the Assad regime and the continuation of attacks and aggression against the people of Syria.