Syria's main, Western-backed opposition groups said Friday they will attend the United Nations-sponsored indirect peace talks with the Damascus government in Geneva, starting in two days' time, amid renewed efforts by the international community to end the deadly, five-year conflict.

The civil war has killed 250,000 people and displaced millions of Syrians from their homes. In the latest violence, Syrian state media reported that the extremist Islamic State group killed Syrian poet Mohammad Bashir al-Ani and his son, Eyas, in the eastern city of Deir el-Zour, which is contested between the government and ISIS.

The opposition groups, assembled under an umbrella known as the High Negotiations Committee (HNC), said in a statement that their participation in the Geneva talks starting Monday comes in response to "sincere" international efforts to end Syria's war.

The decision to go came after violence dropped following a truce brokered by Russia and the United States. That ceasefire went into effect on Feb. 27, and the government and militants allowed dozens of trucks carrying aid to enter besieged areas.

The HNC said it still seeks a full lifting of siege on rebel-held areas, as well as the release of hundreds of detainees including women and children.

The opposition team in Geneva will press for a transitional governing body with full executive powers and a pluralist regime in which President Bashar Assad and his associates will have no role, the HNC statement said. It also insisted on Syria's unity and the restructuring of the country's security agencies.

But the umbrella's chief, Riad Hijab, played down expectations ahead of the Geneva talks.

"We are not going to test the intentions of the (Syrian) regime," he said. "We know what crimes they are committing."

Syrian Foreign Minister Walid al-Moallem is scheduled to hold a news conference on Saturday but it was not clear if he is going to announce when the government's team will head to Geneva.

First talks failed

The first round of Geneva talks collapsed on Feb. 3 during a wide government offensive against insurgents.

Syria's civil war has devastated the country and given space for the emergence of radical militant groups such as the Islamic State and al-Qaeda's branch in Syria, known as the Nustra Front. Those groups and other militant factions are not part of the cease-fire or international negotiations.

In its report about the killing of the poet, al-Ani, the SANA news agency said late Thursday that he and his son were taken from their home in Deir el-Zour two months ago to an unknown destination.

The 56-year-old al-Ani was one of the most prominent poets in eastern Syria.