A fuel ship supplying the Comoros army has caught fire, hindering an anticipated military operation against the Indian Ocean archipelago's rebel Anjouan island, reuters quoted a senior official as saying. Hundreds of troops have gathered on Moheli, the smallest and least developed of Comoros' three islands, in preparation for the expected attack. Anjouan's self-declared leader is defying the central government by refusing to relinquish power. Used to transport fuel for the military, the Tauris caught fire at 0200 on Sunday morning (2300 GMT on Saturday) in the port of Comoros' capital Moroni. "An inquiry has been opened to determine the origin of the fire, whether it was accidental or criminal," government spokesman Abdourahim Said Bacar told Reuters on Sunday.