Indian officials, however, said the information was too vague to act on before the series of attacks on Mumbai in which 179 people died, CNN reported Thursday.

Indian officials said the attackers hijacked a trawler in the Pakistani port city of Karachi, about 575 miles from Mumbai, and went ashore at the Indian financial and entertainment hub in dinghies. Indian officials have said they believe the attacks were conceived and developed in Pakistan.

The fisherman, Damoda Tandel, showed CNN a letter in which he warned Indian authorities that terrorists were using the harbor to import an explosive compound used in military and industrial applications. He says police did nothing.

Two explosives were detonated in taxis during the attack. After the siege, police found one bomb in the Oberoi hotel and two at the Taj Mahal hotel, sites where hostages were taken. Officials found another bomb at a train station but the timer device on the explosive wasn't active.

Tandel told the cable news broadcaster he is concerned that more explosives could be planted around Mumbai, although authorities said they believe all the bombs have been found.

The fisherman said police could have prevented the 10 attackers from reaching shore if they had secured the harbor.

Police said the lone attacker in custody told them the attack was planned in Pakistan three months before it was carried out.