The US and Britain are considering further sanctions against the Syrian government and Russia over the military siege on Aleppo, the country's top diplomats said on Sunday after a meeting in London to discuss the conflict.
US Secretary of State John Kerry dismissed the option of further military intervention in Syria, while British Foreign Secretary Boris Johnson said there was little "appetite" in the West for a military solution, pointing instead to sanctions against the Syrian government and its supporters.
"I think the most powerful weapon we have at the moment is our ability to make President [Vladimir] Putin and the Russians feel the consequences of what they are doing," Johnson said.
The meeting followed Kerry's Saturday talks in Switzerland with the foreign ministers of Russia, Turkey, Saudi Arabia and Qatar.
The Swiss talks, which ended inconclusively, were to continue in the following week, Kerry told German Foreign Minister Frank-Walter Steinmeier on Sunday, according to the German Foreign Ministry.
The flurry of diplomacy comes weeks after a ceasefire deal in Syria collapsed and Washington suspended cooperation with Moscow over its continued bombing of Aleppo.
Sunday saw rebel-held areas of the northern Syrian city again hammered by a wave of air raids and rocket strikes which cost the lives of 31 people, according to the Syrian Observatory for Human Rights.
Also on Sunday, Syrian rebels, backed by Turkish warplanes and tanks, captured the Syrian town of Dabiq from Islamic State, according to a monitoring group.
Dabiq holds great symbolic value for the terrorist group as it is prophesied to become the site of a key battle between Muslims and a Christian army.
Dabiq is also the name of Islamic State's English-language magazine.
The advance comes a day after the rebels started a major offensive to take the town in northern Syria near the Turkish border, the Syrian Observatory for Human Rights added.
The rebels are combing the town for remaining militants, the Observatory added.
The rebels took control of Dabiq after Islamic State fighters were forced to retreat to other areas still under the radical group's control on the outskirts of Aleppo in northern Syria, according to the watchdog.
In August, Turkey invaded northern Syria to attack Islamic State and Kurdish militants.
In recent weeks, Turkey has turned its focus on the jihadist group after the United States urged Ankara, its NATO ally, to refrain from further attacks on the Kurds.