Rebels on the ground in Syria have launched a blistering attack on the Syrian opposition coalition outside the country, BBC News said.

A statement issued by the Revolutionary Movement in Syria said the coalition had failed to represent the Syrian revolution.

The criticism comes amid Russian and US efforts to arrange a conference on Syria in June. An emergency UN debate on Syria is also due in Geneva on Wednesday, May 29.

The statement by grassroots opposition groups inside Syria says the National Coalition has allowed itself to be taken over by regional and international players. Issued in the name of the Revolutionary Movement, it says the Coalition is incapable of fulfilling its duties due to chronic internal discord.

A meeting of National Coalition members in Istanbul has been marked by sharp divisions and a failure to agree on who should represent them at June's conference.

The statement called for at least half the Coalition's leadership bodies to be made up of "revolutionary forces".

It is the clearest sign yet of the total disarray of the opposition leadership, as it faces the challenge posed by the Russian and American call to negotiate with the Syrian regime, BBC News said.