HYDERABAD: AP Police stepped up efforts to trace those behind the bomb attack at the historic Mecca Masjid here even as a forensic expert and a bomb squad from Delhi reportedly found another cellular phone inside the mosque.

A forensic expert and bomb squad of the elite National Security Guard (NSG) visited the mosque and thoroughly searched the premises where a powerful bomb exploded during Friday prayers, killing 16 people and injuring over 50.

The NSG personnel reportedly found a mobile phone and some remnants of the bomb, a worker who helped police in the search said.

Additional Police Commissioner (Coordination) N V Surendra Babu confirmed the NSG's expert team had visited the site but expressed ignorance about the recovery of a mobile phone.

Police are now probing whether the cellphone recovered belongs to any worshipper or was used by those who triggered the bomb.

An eight-member NSG team is here to assess the magnitude of the bomb that was allegedly made with RDX.

The team, with the help of the mosque's workers searched the entire premises including the tank used for performing ritual ablutions after pumping out its water.