The United States must honour promises of support for democracy in Syria, opposition spokesman Walid al-Bunni said on Saturday after his National Coalition canceled visits to Rome, Moscow and Washington.
"Our visit to Washington is on hold until Washington takes a stance that is in accordance with US statements on its support for democracy," Bunni told France 24's Arabic-language channel.
"The United States is a leading force in the world, as are France, Britain and the European Union. All these have been unable to stop a butcher from committing massacres against our people," he said, referring to Syrian President Bashar al-Assad.
The opposition has frequently called for increased military assistance for insurgents fighting Assad's troops in a nearly two-year conflict that the United Nations says has killed some 70,000 people.
Bunni criticised world powers for what he said was a failure to turn into action their statements of support for the opposition.
"The United States, the American people, the European Union, the free world have not done enough to stop what is happening to the Syrian people," he said .
"We cannot continue listening to statements that are not accompanied by action... The world has a responsibility to protect (the Syrian people) from a butcher who has been slaughtering them for two years."
Referring to an upcoming meeting of the Friends of Syria group in Rome, Bunni said: "We want to say to (pro-opposition countries that comprise the group): if you are our real friends, help us to stop the massacres that are being committed against our people."