A man rides a motorbike past damaged buildings covered with snow in the rebel-controlled area of Maaret al-Numan town in Idlib province, Syria, January 5, 2016.Reuters

Days after the Bashar al-Assad government in Syria told the United Nations that it will participate in the peace talks scheduled for this month in Geneva, a Syrian opposition leader has raised doubts if the 25 January talks will take place. 

George Sabra, a Syrian politician, told Reuters that the date set for the peace talks between the Syrian government and the opposition groups was not "realistic". 

"I personally do not think Jan. 25 is a realistic date for when it will be possible to remove all obstacles facing the negotiations," he said. 

Last week, Syrian Foreign Minister Walid al-Moallem told UN special envoy to Syria Staffan de Mistura that the government would participate in the Geneva meeting

The date was fixed after the United Nations Security Council adopted a peace resolution last month, in which it called for elections to be held within 18 months in Syria. 

On Wednesday, de Mistura said that the Geneva meeting was still on track, according to Reuters

Syrian rebel groups have threatened to boycott the meeting unless their demand for the implementation of the key humanitarian articles of the UN resolution is met. 

The groups have urged humanitarian access to those in need and a stop on attacks on civilians, as prescribed under articles 12 and 13 of the UN resolution. 

Meanwhile, the Syrian opposition council has called for the release of some prisoners before 25 January. 

The five-year civil war in Syria has killed over 2,50,000 and displaced lakhs of people.