Two more persons have been arrested in connection with the December 28 terrorist attack at the Indian Institute of Science, raising the total number of those arrested to six, police said.

Police said Nizamuddin alias Munna, 24, and M Noorulla Khan, 25, both residents of Chintamani in Kolar district in Karnataka, were taken into custody near Hesaraghatta on the city outskirts on Sunday.

The six arrested were in constant touch with each other and had also participated in meetings in Bangalore and were preparing to carry out "violent militant activities" in and around Bangalore, police said.

Based on the information given by Nizamuddin, an electrician, and Noorulla, an auto driver, police recovered two 'tin' bombs, a 'tiffin-carrier' bomb, a country-made revolver with three rounds, three electrical detonators and a telephone book that had numbers of other members of the gang.

Police said the two, who are now in police custody for further interrogation, were "very keen" to undergo terrorist weapon-training plan drawn by Afsar Pasha, who was arrested earlier.

All the four arrested earlier were Lashkar-e-Taiba militants.

M C Puri, a retired professor of the Indian Institute of Technology, Delhi, was killed and four others were injured in the terror attack.