The Taj Mahal Palace hotel was among the gunmen's targets
Indian police have arrested two men in the eastern city of Calcutta suspected of handling mobile phone cards later used by the Mumbai attackers.
A police spokesman said the two were arrested over a fraud investigation, but that they were suspected to have supplied the attackers with the cards.
Police said the two had been arrested on Friday and were now being questioned.
At least 170 people died in attacks on several landmarks in the city.
Nine of the 10 militants believed to have mounted the attack were among the dead, while a 10th suspect is in custody.
Senior Calcutta police official Javed Shamim told the BBC that the arrests were in connection with 40 Subscriber Identity Module (SIM) cards which were believed to have been bought using fraudulent methods.
Some of these cards are later suspected to have been used by the Mumbai attackers.
Islamabad on edge
In a separate development, Pakistani media reported that Pakistan went on high alert during the attacks after an alleged hoax call to President Asif Ali Zardari.
A caller claiming to be Indian Foreign Minister Pranab Mukherjee spoke to the Pakistani leader in a threatening manner on 28 November, the Dawn newspaper reports.
Asked by Reuters news agency for comment, a diplomat with knowledge of the exchanges said the report was accurate.
Pakistan's air force was placed on "highest alert" for 24 hours as a consequence.
India and Pakistan, which both possess nuclear weapons, have fought several wars since partition in 1947.
Militants arriving by dinghy attacked Mumbai on the night of Wednesday 26 November, targeting two luxury hotels, the main railway station, a hospital, a Jewish centre, a cafe and other sites.
Crowds were sprayed with gunfire indiscriminately and hostages at the Jewish centre were found shot dead. Those killed included 26 foreigners.
It took Indian security forces nearly three days to eliminate the last of the attackers, who were holed up in the iconic Taj Mahal palace hotel.
Commentators have described the assault as "India's 9/11", in reference to the suicide plane attacks on the US in 2001.
A claim of responsibility was made by a previously unknown Islamic militant group calling itself the Deccan Mujahideen - a reference to a mainly Muslim region of India.
Indian media have named the surviving gunman as Azam Amir Qasab, a Pakistani, and say he has links to a Pakistan-based Kashmiri militant group, Lashkar-e-Taiba. The group denies involvement.
Pakistan's government has strongly denied any involvement in the Mumbai attacks and its Foreign Minister, Shah Mahmood Qureshi, said his country would co-operate with India to "combat terrorism in all its forms and manifestations".
Indian ministers have themselves come under immense public pressure for failing to prevent the attacks and the government has moved to beef up the navy and the air force.
But the new Home Minister, Palaniappan Chidambaram, said India would remain a "secular, plural, tolerant and open society" despite the attacks.