One person has been arrested on charges of writing anonymous letters threatening to blow up trains in Tamil Nadu. Mohammed Din Ul Aris, who belongs to Melapalayam of Tirunelveli, was arrested by Railway Police on Tuesday.

He has been remanded to judicial custody by a Madurai court, police said on Wednesday. Aris is the brother of 'Manga' Basheer, who was killed along with Imam Ali in the shootout at a Bangalore hideout in September 2002.

Imam Ali, said to be an ISI agent, had earlier escaped from Madurai police custody in March, 2002. Police said Aris sent 'anonymous letters' to the station masters of Salem, Tirunelveli, Madurai and Chennai Egmore, threatening to blow up 10 trains to avenge the torture' of innocent Muslim prisoners.

After keeping a close watch on suspects, police subjected their handwritings to forensic tests and arrested Aris as his handwriting matched with that of the anonymous letters.