Syria's foreign minister said Friday that airstrikes against the Islamic State group "are useless" unless they are co-ordinated with the Syrian government, as the international community scrambled to respond to Russia's airstrikes in his country.

Addressing the summit of world leaders at the UN General Assembly, Walid al-Moallem said Russia's decision to start bombing targets was based on the Assad government's request and is effective because it supports Syria's efforts to combat terrorism.

"Terrorism cannot be fought only from the air, and all of the previous operations to combat it have only served its spread and outbreak," al-Moallem said.

"Airstrikes are useless unless they are conducted in co-operation with the Syrian army, the only force in Syria that is combating terrorism," he added.

Moscow, a longtime ally of Syrian President Bashar Assad, began launching airstrikes in Syria this week, adding another layer of tension over the war. The Syrian army had already been joined by Lebanon's Shiite Hezbollah militia.

The United States, which opposes Assad and is firing its own airstrikes against extremists in Syria, has questioned Moscow's assertion that it is targeting Islamic terrorists there, saying the areas hit close to Homs are strongholds of the Syrian opposition to Assad. Allies in the U.S.-led coalition have called on Russia to cease attacks on opposition forces and to focus on fighting Islamic State militants.

He pledged to continue the war against "terror" while also committing to a political track to end Syria's civil war, which is now in its fifth year and has killed more than a quarter of a million people. An estimated 4 million people have fled.

Al-Moallem also said that his country's army "is capable of cleansing the country of those terrorists" and warned about the threat of a growing "caliphate state, which as you know, will not be limited to Syria or Iraq."

Al-Moallem announced Syria will participate in UN-led working groups toward a third round of peace talks in Geneva.

The UN's envoy to Syria, Staffan de Mistura, has proposed four working groups on Syria as part of his latest efforts to bring Syria's parties together toward a long-elusive agreement to end the conflict.

The groups are to hold simultaneous discussions among Syrian parties on issues such as protection of civilians, combatting terrorism and political issues.

Al-Moallem stressed that the working groups proposed de Mistura are non-binding. The foreign minister described them as "brainstorming" sessions meant to prepare for the launch of new peace talks sometime in the future.

But he added: "How can we ask the Syrian people to head to the ballot box while they are not safe in the streets?"

World leaders also tried to address the crises in Libya and Yemen with high-level meetings on Friday.

U.S. Secretary of State John Kerry and UN Secretary-General Ban Ki-moon urged Libya's two rival governments to come together and make the final step toward a peace deal.

But talks between representatives of the two governments on the sidelines of the UN gathering of world leaders have not yet resulted in a signed agreement, even as a UN-set deadline of Oct. 2 approaches.

Ban said a final draft is in the two sides' hands, and "the time for reopening the text has passed." He said the UN envoy for Libya, Bernardino Leon, has assured him that the parties "remain committed and will not go back on their word."

Kerry told the meeting that he hopes the process can be "completed in a very small number of days," and he urged the two sides to agree on who will lead a national unity government.

The oil-rich north African country has slid into turmoil since the 2011 overthrow and killing of longtime dictator Moammar Gadhafi.

Also addressing the General Assembly on Friday was interim Burkina Faso President Michel Kafando, who was arrested by members of the elite presidential guard during a short-lived coup and then released last month.

Kafando pledged that free and transparent elections will be organized "shortly."