Iranian President Hassan Rouhani on Monday called for a united front to fight extremists in the Middle East and said Tehran was ready to help "bring about democracy" in Syria and Yemen.

Making his first address to the U.N. General Assembly since the historic nuclear deal was reached, Rouhani waded into the intense diplomatic debate over fighting jihadists and pushing for regime change in Syria.

France on Monday gave cautious backing at the United Nations to a call from Russian President Vladimir Putin for a "broad coalition" to fight the Islamic State group in Syria.

Speaking to the U.N. General Assembly, French President Francois Hollande called such a coalition "possible, desirable, necessary" but said it would have to have "a clear basis, otherwise it would never come to light."

Russian President Vladimir Putin on Monday called for a "broad coalition" to fight the Islamic State group in Syria, in his address to the U.N. General Assembly.

Putin likened the coalition to the "anti-Hitler" alliance that fought together during World War II and said Muslim countries "should play a key role."

President Bashar Assad has gone from pariah to potential partner, bolstered by his allies Russia and Iran in Syria's four-year war and Western concern about the jihadist threat, experts say.

In power for 15 years, Assad is virtually the sole survivor of the Arab uprisings that have unseated rulers across the Middle East and North Africa.

Fifteen civilians, including five children, were killed in regime air raids on a popular market in a jihadist-held city of eastern Syria on Monday, a monitoring group said.

"Regime military aircraft fired at least two missiles at a busy souk in the city of Mayadeen, killing 15 civilians including five children and three women," said Rami Abdel Rahman, head of the Syrian Observatory for Human Rights.

U.S. President Barack Obama on Monday took a swipe at Russia and Iran for backing what he called "tyrants" like Syria's Bashar Assad but declared in his address to the United Nations that he was ready to work with them to end the conflict.

Obama took the podium at the U.N. General Assembly ahead of President Vladimir Putin and Iranian leader Hassan Rouhani, with the spotlight firmly on ending the carnage in Syria.

Turkey's Prime Minister Ahmet Davutoglu on Monday ruled out creating a processing center for the thousands of mostly Syrian migrants trying to enter Europe from Turkish territory, calling instead for them to be hosted in "safe zones" inside Syria.

Responding to repeated calls by EU members for migrants' asylum claims to be handled in the countries from which they set sail for Europe, Davutoglu told Hurriyet newspaper: "We have told Europe that there will be no reception center in Turkey."

Russia and the United States are expected to take part in Syria peace talks in October, along with Iran, Saudi Arabia, Turkey and Egypt, Russia's deputy foreign minister said Monday.

A meeting of an international contact group of the "most influential outside players" will "be pushed forward to October after the U.N. General Assembly," deputy foreign minister Mikhail Bogdanov said, quoted by RIA Novosti news agency.

The number of Australians fighting for the Islamic State group in Syria and Iraq doubled in the past year but was not expected to continue to grow so rapidly, Foreign Minister Julie Bishop said.

Australia has been increasingly concerned about the ability of IS, also known as Daesh, to lure citizens to the conflict and at least 20 nationals are believed to have died there.

Republican firebrand Donald Trump has promised to scrap taxes for America's poorest and offer healthcare for all if elected president -- paid for by renegotiating the NAFTA accords and picking a trade fight with China.

The Republican presidential frontrunner and billionaire businessman promises to unveil Monday what the national economy would look like under a President Trump.