Two Russian military pilots were killed when their helicopter crashed near the central Syrian city of Homs, the defense ministry said on Tuesday, adding that the aircraft had not been under fire.

"Two crew members died," the defense ministry said in a statement.

At least 24 Islamic State group fighters and eight civilians were killed in air strikes Sunday on Syria's Raqa, the de facto capital of the jihadist movement, a monitor said.

A dangerous terrorist cell was uncovered recently in the North by the General Security, reported As Safir newspaper on Saturday.

Widely informed security sources told the daily that the extremists were using a religious school as a front for jihadist dealings.

Denmark's government said Friday it wanted to ban travel to areas where terror groups are operating in conflict zones in a bid to facilitate the prosecution of fighters returning from Syria.

The move came a day after four men were arrested in the Copenhagen area on suspicion of having joined the Islamic State jihadist group while in Syria.

U.N. Syria envoy Staffan de Mistura said Thursday that the next round of peace talks will begin on April 13 after he completes a diplomatic tour, including stops in Damascus and Tehran.

The United Nations had previously said that the negotiations in Geneva would resume on April 11 after the last round ended on March 24.

The United Nations said Thursday it is aiming to begin a large-scale evacuation of wounded and sick people from four besieged towns in war-ravaged Syria within the next week.

Jan Egeland, who heads a U.N.-backed humanitarian taskforce for Syria, said "a very major" medical evacuation was planned for Madaya and Zabadani, two towns near Damascus blockaded by the regime and their allies, and Fuaa and Kafraya, which are besieged by rebels in Syria's northwest.

U.S. and Turkish authorities are discussing plans to intensify support to the moderate Syrian opposition in a bid to push the Islamic State group back from the Turkish border, the U.S. Ambassador to Ankara said Thursday.

"We have had some progress in recent weeks as these groups pushed further east along the border," John Bass told journalists.

The General Security agency announced on Thursday the arrest of a Syrian member of the extremist Islamic State group.

The suspect, identified as M.F., confessed to taking part in clashes against the army in the northeastern border town of Arsal in 2014.

Al-Qaida's Syrian affiliate confirmed on Wednesday the death of its spokesman Abu Firas al-Suri in a U.S. air strike earlier this week.

In a statement circulated on Twitter, Al-Nusra Front said Suri and other members "were killed during a Crusader (Western) air strike... on April 3, 2016."

German authorities Wednesday arrested a Syrian national on war crimes charges, on suspicion of commanding a rebel militia in Aleppo that committed atrocities and plundered artifacts for sale.

Federal prosecutors said in a statement that the 41-year-old accused identified only as Ibrahim Al F. had been detained in the western region of Westphalia on a German arrest warrant.