U.S. Secretary of State John Kerry says there can be no peaceful solution to the conflict in Syria as long as President Bashar al-Assad remains in power.
Kerry spoke Monday after meeting separately with Qatari Foreign Minister Khalid al-Attiyah and with Saudi Foreign Minister Prince Saud al-Faisal, responding to reports that Mr. Assad intends to run for re-election next year.
"Now I don't know anyone who believes the opposition will ever consent to Bashar al-Assad being part of that [transitional] government. And if he [Bashar al-Assad] thinks he's going to solve problems by running for re-election I can say to him, I think with certainty, this war will not end as long as that's the case or he [Assad] is there."
Kerry travels 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.
Kerry called the need for such a conference urgent.
"There are more and more refugees, more and more displaced people, more and more destruction and the potential for the absolute implosion of the state of Syria is what lies in front of everybody if there cannot be a negotiated solution."
Officials have given conflicting signals in the past week about whether a date for the talks has been set. U.S. officials say they hope the conference can take place as soon as late November.
Setting a date will likely be up to United Nations and Arab League envoy Lakhdar Brahimi. He gave a somber assessment of the situation in Syria during a stop in Baghdad Monday.
''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 President 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 a senior commander 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.