UPFA Parliamentarian Kumara Welgama attended the Api Sri Lanka convention, which is currently underway at the Sugathadasa Indoor Stadium.
Welgama identifies himself as the third most senior member of the SLFP.
The event is being held under the patronage of former President Chandrika Bandaranaike Kumaratunga.
Several SLFP seniors including Athauda Seneviratne are also attending the rally.
The SLFP has warned that it will take disciplinary action against members attending the rebel convention.