Iran accused the United States Sunday of not taking the threat from Islamic State militants in Iraq and Syria seriously, and charged that U.S. aid had previously helped the jihadists.

Secretary of State John Kerry discussed Saturday the Islamic State threat with the head of the Arab League, ahead of the group's next round of discussions.

Fierce clashes erupted on Saturday evening in the Wadi al-Raayan area in the outskirts of the Bekaa town of Arsal which borders Syria, state-run National News Agency reported.

“The sounds of rockets and shells are being heard in the northern Bekaa's towns,” NNA said.

Syrian air strikes in the jihadist-held northern city of Raqa on Saturday killed 31 people, including 15 Islamic State (IS) members, a monitoring group said.

"Regime warplanes carried out eight air strikes targeting Raqa and its surroundings," said Syrian Observatory for Human Rights director Rami Abdel Rahman.

The U.S. and its allies are trying to hammer out a coalition to push back the Islamic State group in Iraq. But any serious attempt to destroy the militants or even seriously degrade their capabilities means targeting their infrastructure in Syria.

That, however, is far more complicated. If it launches airstrikes against the group in Syria, the U.S. runs the risk of unintentionally strengthening the hand of President Bashar Assad, whose removal the West has actively sought the past three years. Uprooting the Islamic State group, which has seized roughly a third of Syria and Iraq, may potentially open the way for the Syrian army to fill the vacuum.

U.S. plans to forge a coalition to defeat Islamic militants are not modeled on the global front brought together for the heavily-criticized 2003 invasion of Iraq, American officials insisted Friday.

"When we talk about what we are doing today, in no way do we want to resemble anything that was done in 2003 in the invasion of Iraq," State Department deputy spokeswoman Marie Harf told reporters.

Russian Ambassador to Lebanon Alexander Zasypkin warned of the threat of Islamist extremists on Lebanon given its spread in Iraq and Syria, reported As Safir newspaper on Saturday.

He told the daily: “Lebanon has turned into a front to confront the Islamic State group, but it is not directly connected to the situation in Iraq and Syria.”

The municipal chief of the northeastern border town of Arsal questioned the delay in the release of the soldiers and policemen held captive by Islamist militants, reported al-Liwaa newspaper on Saturday.

Ali al-Hujairi told the daily that a Syrian mediator, not a Qatari one, was leading the negotiations on the release of the abductees.

Islamic State fighters executed a youth in a Syrian town Friday, after hundreds of residents demanded they leave following regime air strikes that targeted the jihadists but killed eight civilians, a monitor said.

Residents of Ashara, in the mostly IS-controlled eastern province of Deir Ezzor, protested in front of an IS headquarters Thursday evening, hours after air strikes killed two children, five women and a man, Syrian Observatory for Human Rights director Rami Abdel Rahman said.

A ministerial panel following up on the case of the abducted troops convened on Friday amid a boycott by the hostages' families, as the Islamic State group accused Qatari mediators of maneuvering and “obstructing the negotiations” before eventually meeting with them.

“Prime Minister (Tammam) Salam expressed his relief over the political consensus that was demonstrated during the (Thursday) cabinet session regarding the principles that must govern the issue,” Defense Minister Samir Moqbel told reporters after the meeting.