U.S. Secretary of State John Kerry has arrived in Paris for talks with Qatari Foreign Minister Khalid al-Attiyah about Syria.
The two men will then travel to London Tuesday for a meeting with other core members of the Friends of Syria and the Syrian opposition.
The talks come as efforts continue to convene a long-sought Syrian peace conference that would bring together Syria's government and the opposition with a goal of negotiating a political settlement to the country's crisis.
Officials have given conflicting signals in the past week about whether a date for the talks has been set.
During a stop in Baghdad Monday, U.N.-Arab League envoy Lakhdar Brahimi gave a somber assessment of the situation on the ground.
''The Syrian crisis is too serious and dangerous not only for the Syrian people but the region and world alike. I think all people, who are concerned with the affairs of the region, have unanimously agreed that the Syrian crisis is the most serious one in the world and it threatens world peace and stability. In fact, the international community is too late to offer help to the Syrian people.''
Opposition leaders have threatened to boycott the proposed peace conference unless Syria's President Bashar al-Assad agrees to step down. Mr. Assad insists he will remain in office until his term ends in 2014, and possibly seek re-election as well.
Tuesday's meeting in London will bring together officials from Britain, Egypt, France, Germany, Italy, Jordan, Qatar, Saudi Arabia, Turkey, the United States and the United Arab Emirates.
Meanwhile, opposition activists and state media say one of the most senior commanders in the rebel Free Syrian Army has been killed. Yasser al-Abboud was reportedly killed Monday while participating in an attack on government forces in the town of Tafas.
Al-Abboud was one of the first high-ranking military officials to publicly defect from the regime and join the rebels.
The fighting in Syria has killed more than 100,000 people and forced millions from their homes since March 2011.