A Turkish citizen fighting in Syria who Moscow has accused of killing a Russian pilot said Friday he was not scared Russian forces are targeting him, after making an unexpected public appearance in Istanbul.

Alparslan Celik has been accused by Russia of killing in cold blood Russian pilot Oleg Peshkov as he parachuted to the ground after his plane was shot down by Turkish air forces on the Syrian border on November 24.

A suicide bomber attacked a mosque in Shiite-populated eastern Saudi Arabia during Friday prayers, killing four people before worshipers disarmed and tied up his accomplice who had fired on them.

The state Al-Ekhbariya news channel quoted an interior ministry spokesman as saying four people died and 18 were wounded.

U.S. and British intelligence agencies for years hacked into Israeli drones carrying out surveillance to prepare for a potential strike on Iran, Israeli daily Yediot Aharonot reported on Friday.

Citing documents leaked by rogue U.S. intelligence contractor Edward Snowden, Yediot said that the operation, codenamed "Anarchist", began in 1998 at a British facility in the Troodos mountains of Cyprus and a U.S. National Security Agency (NSA) site at Menwith Hill, in northern England.

Syria's largest mainstream opposition group will attend U.N.-brokered talks in Geneva, a senior delegate told AFP on Friday after four days of discussions in Riyadh.

The delegate said the Saudi-backed High Negotiations Committee will send "about 30, 35 people" in all to Geneva, where talks got underway Friday.

Iran's Revolutionary Guards has recruited thousands of Afghans, some by coercion, to fight in Syria's war alongside forces loyal to President Bashar al-Assad, Human Rights Watch said Friday.

"Iran has not just offered Afghan refugees and migrants incentives to fight in Syria, but several said they were threatened with deportation back to Afghanistan unless they did," said Peter Bouckaert, emergencies director at the New York-based HRW.

President Barack Obama on Thursday said the United States would tackle the Islamic State group beyond Iraq and Syria if necessary, as he signaled an increased focus on Libya.

Amid fears that a power vacuum in the north African nation has provided fertile ground for Islamic State to grow, Obama convened his National Security Council to discuss the issue.

Syrian defense minister Fahed Jassem al-Freij on Thursday met his Russian counterpart Sergei Shoigu in Moscow ahead of Syria peace talks due to start Friday in Geneva. 

"The results of the operation of the Russian air force in Syria, aimed at the destruction of terrorist groups, were discussed," Russian news agencies quoted the defense ministry as saying.

The life of imprisoned Palestinian journalist Mohammed al-Qiq is in danger from his 64-day-old hunger strike, the International Committee of the Red Cross said on Thursday.

"Mr. Qiq has been on hunger strike for more than 60 days and has entered a critical stage, his life being at risk," the ICRC said in a statement.

The U.N.'s Syria envoy warned peace talks due to be held in Geneva must not fail, but members of the fractious opposition said they would miss the start on Friday.

Delegates from the Saudi-backed High Negotiations Committee said late Thursday that discussions in Riyadh over whether to attend the U.N.-brokered talks would continue the next day.

The United States is monitoring Iraq's largest dam for signs of further deterioration that could point to an impending catastrophic collapse, U.S. army officers said on Thursday.

The Islamic State (IS) jihadist group seized the Mosul Dam briefly in 2014, leading to a lapse in maintenance that weakened an already flawed structure, and Baghdad is seeking a company to make repairs.