A two-day G8 summit gets under way in Northern Ireland on June 17 with the Syrian conflict expected to be high on the agenda.
Syria will also likely be the focus of talks on the sidelines of the summit between Russian President Vladimir Putin and U.S. President Barack Obama.
The United States last week announced it would arm Syria's rebels after claiming the regime of Bashar al-Assad had used chemical weapons.
On June 17, Russia's Foreign Ministry said Moscow will not permit a no-fly zone to be imposed over Syria. Spokesman Aleksandr Lukashevich said that calls for a no-fly zone showed disrespect for international law.
Lukashevich said Russia did not want a scenario in Syria that would repeat the events in Libya, where a no-fly zone enabled NATO aircraft to help rebels overthrow Muammar Qaddafi.
On June 16, Putin defended his administration's arming of Assad, saying Russia was not breaking international law.
"But if we speak calmly and professionally, then I want to draw your attention to the fact that Russia supplies arms to the legitimate government of Syria in full compliance of international law. We are not breaching any laws. Let me emphasize that: nothing. We call on all our partners to act in the same fashion," Putin said.
Putin questioned why the West would want to arm Syrian rebels, who he said ate human organs.
"I believe one does not really need to support the people who not only kill their enemies, but open up their bodies, eat their intestines in front of the public gaze and cameras," Putin said. "Are these the people you want to support? Are they the ones you want to supply with weapons?"
He was speaking after talks in London with British Prime Minister David Cameron, who said it was crucial Assad was removed from power.
"Almost 100,000 people have lost their lives in this war. The daily crimes there plumb new depths in the history of the region," Cameron said alongside Putin at a press conference following their talks. "Every month that passes leaves more dead, and Syria more dangerous to the region and to all of us. We must work together to do everything we can to bring this dreadful conflict to an end."
Cameron also said Russia and Britain can overcome their differences on Syria.
Besides Syria, Cameron wants the G8 summit to produce new agreements on tax, trade, and financial transparency.
The G8 summit is also likely to consider the impact of the election of moderate cleric Hassan Rohani as Iran's new president.
Cameron is being joined by Obama, Putin, and the leaders of France, Germany, Italy, Canada, and Japan.
With reporting by dpa and Reuters