World leaders converged Sunday for a summit in Turkey to send a message of unity in the face of the Paris attacks but confronting a gaping divide over the multiple conflicts tearing Syria apart.

US President Barack Obama, Chinese President Xi Jinping and Vladimir Putin of Russia will join other leaders in the southern Mediterranean resort of Antalya less than two days after the attacks claimed by Islamic State militants killed at least 129 people and sent shockwaves across the world.

The character of this Group of 20 summit has been transformed by the attacks, with security and the Syrian conflict now eclipsing a traditionally financial agenda that must also deal with the spreading refugee crisis, climate change and tax avoidance.

An official in the French delegation, led by Foreign Minister Laurent Fabius after President Francois Hollande stayed home to lead his shaken nation, said it was expected that during the meetings "there would a particular emphasis on terrorism".

The gathering offers the first possibility of a meeting between Obama and Putin since Russia launched its declared anti-Islamic State air campaign in Syria, which the West suspects is aimed at propping up the regime of President Bashar al-Assad.

The White House has said there may be an informal meeting between the pair, whose icy body language at previous encounters has grabbed as many headlines as their comments. No formal summit is scheduled, however.

Host President Recep Tayyip Erdogan, who wants to use the summit to cement his status as a global leader after a resounding election victory this month, has called on the world to forge a stronger "consensus" on terror in the wake of the attacks.

But whereas even the likes of Putin and Obama will have no trouble standing together in shared abhorrence of terrorism, overcoming differences on Syria will prove far trickier.

No music at shaken summit

All musical events, including at the official dinner on Sunday night, have been cancelled as a mark of respect for the victims of the Paris attacks for the summit, which officially kicks off at midday Sunday (1000 GMT), Turkish presidential sources said.

The leaders will likely struggle to find common ground over the Syria crisis, with hosts Turkey deeply opposed to Russia's air strikes and finding only a lukewarm reaction so far to its proposal for a safe zone free of Islamic State jihadists to be created inside Syria as a haven for refugees.

"I pray and hope that G20 will provide a platform whereby all of these issues can be discussed openly and then we can understand each other," Erdogan said ahead of the summit.

Top diplomats gathered in Vienna on Saturday agreed a fixed calendar for Syria that would see a transition government in six months and elections in 18 months but failed to agree on the future of Assad.

Yet officials in Antalya have also insisted that they will not allow those behind the Paris attacks to derail the summit from achieving its original aims.

The refugee crisis is a key topic, with host Turkey housing some 2.2 million Syrian refugees from the conflict but the European Union wanting Ankara to do more to prevent migrants undertaking risky boat crossings to the EU.

Discussions on climate change will assume greater importance than usual coming just ahead of the UN COP21 conference in Paris that aims to agree a legally binding global climate treaty.

Campaigners will be hoping that a change of leadership in Canada and Australia -- whose previous premiers had shown scepticism about the climate drive -- will help encourage progress.

Other key guests at the summit include Saudi King Salman, whose delegation according to the Hurriyet daily has booked 546 hotel rooms at a cost of up to 15,000 euros ($16,115) each and hired 400 luxury cars.