Tunisia\'s major labor union said Wednesday that it was alerted by the ministry of interior of a potential attack against its leadership, a plot that apparently attempts to thwart a planned national dialogue. Ghassen Ksibi, a media official of the union, or UGTT, said the attackers will probably target the secretary general and other prominent figures, adding \"the bombing of the UGTT headquarters\" could happen. The UGTT has been playing a major role in mediating between different parties to end the ongoing crisis triggered by the assassination of opposition leader Mohamed Brahmi in late July. \"Obviously, targeting the Union means targeting the national dialogue,\" said Ksibi, adding new security measures have been put in place around the union headquarters in downtown Tunis. Tunisia has witnessed two political assassinations this year. Before Brahmi, prominent opposition figure Chokri Belaid was killed in February. The interior ministry has said conservative religious group Ansar al-Sharia, suspected of having ties with al-Qaida in the Islamic Maghreb, may have been involved in both assassinations.