By Dasha Afanasieva and Khaled Yacoub Oweis
ISTANBUL/AMMAN (Reuters) - The Syrian National Coalition named a provisional government for rebel-held areas on Tuesday, despite U.S. misgivings, members of the fractious Western-backed opposition grouping said in Istanbul.
Washington and its European allies hope a proposed peace conference in Geneva will produce an interim government that can help end the armed conflict raging in Syria since 2011 - a scenario they fear the coalition's decision could disrupt.
"The United States is against the provisional government because it thinks it will undermine the Geneva talks," said an opposition official who was involved in naming the cabinet.
"The feeling in the coalition is that even if Geneva convenes it will be a long process and we cannot continue to leave the liberated areas prey to chaos in the meantime."
The coalition serves as a channel for Western support for the rebels, but its leaders are all outside Syria and their influence on disparate rebel factions is patchy at best.
According to the United Nations, some 40 percent of Syria's population need humanitarian assistance. Polio has broken out and people in besieged areas may face malnutrition, but violence and red tape have obstructed aid efforts.
The opposition agreed on Monday to attend peace talks that Washington and Moscow are trying to convene in Geneva but said President Bashar al-Assad could play no part in Syria's future.
The coalition official said it would be hard for the interim government to move to Syria immediately due to the risk of attack from Assad's forces or al Qaeda-linked militants.
He said the cabinet would probably operate from the Turkish border city of Gaziantep, north of the contested city of Aleppo.
In September the coalition led by Ahmed Jarba appointed Ahmed Tumeh, a moderate Islamist, as provisional prime minister, even though U.S. Secretary of State John Kerry had called Jarba and asked him not to form a government, opposition members said.
They said the new cabinet was unlikely to win international recognition, but could attract money from Saudi Arabia, which has been at odds with Washington over Syria, and from foreign donors looking to channel humanitarian aid more efficiently,
Some Western nations, they said, were willing to use the government as an aid channel, without formally recognizing it.
French Foreign Minister Laurent Fabius, in a statement on Tuesday, welcomed the coalition's decision to join the Geneva peace talks as "a major step towards a political solution".
He said the formation of the interim cabinet showed the coalition's "spirit of responsibility" and that France backed efforts to gain immediate humanitarian access to civilians.
Jon Wilks, the British envoy to the Syrian opposition, said forming the cabinet was "an important step" and that Britain was ready to help it deliver services and aid inside Syria.
Among the government's main figures is Saudi-backed dissident Asaad Mustafa, who was named as defense minister. Asaad is a former agriculture minister in Assad's government.
Ibrahim Mero, a Dutch-educated economist, was chosen as finance minister and Taghreed al-Hajlee, the only woman among the nine ministers, for the family and women portfolio.
No one was appointed to the interior, education and health ministries because nominees failed to win the support required.
(Additional reporting by John Irish in Paris; Editing by Alistair Lyon)