Journalist Firas Hatoum and his colleague Rony Rmaity were temporarily detained by Turkish authorities on Tuesday for illegally entering the embattled Syrian town of Kobane, reported al-Akhbar daily.

It said that the LBCI television journalist was seeking to film a report for the channel from Kobane, but the advances made by the Islamic State group in the area forced him to alter his plans.

U.S. President Barack Obama on Tuesday confirmed the death of Kayla Jean Mueller, who was taken hostage in Syria by the Islamic State group, and vowed to track down her captors.

"No matter how long it takes, the United States will find and bring to justice the terrorists who are responsible for Kayla's captivity and death," he said in a statement.

Lebanon's Hizbullah has taken the lead role on a key frontline in southern Syria near the border with the Israeli-occupied Golan Heights, a monitoring group said Tuesday.

A Syrian military source confirmed Hizbullah was engaged in fighting in Quneitra and Daraa provinces as part of efforts to stop rebels advancing in the area.

Syrian activists on Tuesday accused Jaysh al-Islam, a powerful Islamist group near Damascus, of detaining a group of their colleagues, in what they said was the latest in a string of abuses.

"An armed group believed to be loyal to Jaysh al-Islam stormed the office of Erbin's local (activist) committee... It kidnapped the team there and took them to an area near the frontline," said the non-violent Local Coordination Committees activist group.

Damascus receives "information" about air strikes by the U.S.-led coalition against the Islamic State group in Syria, President Bashar Assad said in an interview published on Tuesday.

"Sometimes, they convey a message, a general message," he said in an interview with the BBC in Damascus.

Syrian Kurdish forces have set their sights on taking back from jihadists Tal Abyad, another strategic town on the border with Turkey, after recapturing Kobane, a monitor said Monday.

Tal Abyad, located about 65 kilometers (40 miles) east of Kobane, is an Arab and Kurd town in the Syrian province of Raqa used by jihadists of the Islamic State group to cross into Turkey.

Bahrain's ruler has told his Jordanian counterpart that he is ready to assist the kingdom in its fight against the Islamic State group, the royal palace in Amman said Monday.

King Hamad of Bahrain, quoted in a palace statement, told King Abdullah II that he was "proud to provide all the help Jordan needs to combat terrorism and protect Islam from Daesh (IS)."

At least 15 people were killed and dozens wounded on Monday in government air strikes on an area outside the capital Damascus, the Syrian Observatory for Human Rights monitor said.

There were no immediate details on the breakdown of those killed in the strikes, which are the latest to hit the town of Douma in the rebel stronghold of Eastern Ghouta.

Syria will not allow foreign ground troops on its territory to fight the Islamic State group, Foreign Minister Walid al-Muallem said on Monday.

Speaking at a news conference in Damascus, Muallem also said Jordan had not responded to a Syrian request to coordinate efforts against IS after the group killed a captured Jordanian pilot.

Tokyo defended Monday its confiscation of the passport of a Japanese journalist planning to travel to Syria, as the country reels from the execution of two citizens by Islamist extremists.

Chief Cabinet Secretary Yoshihide Suga said the government took travel documents away from freelance photographer Yuichi Sugimoto, 58, for his own safety, after learning of his plan to cover refugee camps in the war-torn country.