Former H-Block hunger striker, Bernard Fox complained that Gerry Adams and Martin McGuinness, who left the Army Council last year, were effectively running it from behind-the-scenes, the sources said.

Fox could not be contacted for comment.

Sources told the Sunday Tribune he had a "blazing row" with McGuinness before he resigned. Fox (55) joined the IRA at 18 and is extremely popular with grassroots.

Meanwhile, two South Derry Sinn Fein councillors, including the brother of IRA hunger striker Francis Hughes, have resigned. Patsy Groogan and Oliver Hughes are said to have had serious disagreements with the leadership.

Martin McGuinness, who has previously denied that serious splits exist in the area, described the resignations as "most unfortunate". The IRA's entire South Derry brigade recently resigned. The latest resignations will be an enormous blow to Sinn Fein locally. Sources said Bernard Fox's resignation is significant because he is from west Belfast. Until now, most opposition has come from rural areas. Belfast, and in particular the west of the city, has been a leadership stronghold.

Fox has not linked up with dissident groups. He has been imprisoned on four occasions, serving 22 years in jail. He joined the Army Council last year, replacing Brian Keenan who was then ill with cancer.

At the same time, Adams, McGuinness and Martin Ferris resigned their Army Council seats in an attempt to publicly distance Sinn Fein from the IRA. However, Adams and McGuinness continued to exercise power on the Army Council despite their formal departure. One republican said Fox had protested strongly about "a council within a council". One source said Brian Keenan had visited Fox's home to try to talk him out of resignation. The IRA had since taken Fox's 'staff ' car from him, much to the annoyance of some activists. However, another source said he wouldn't be surprised if the internal row was resolved.

An apprentice coach-builder from the Falls Road, in 2001 the DUP's Peter Robinson named Fox in the Assembly as the IRA's director of engineering.