The Indian government is coming under pressure over reports that it had prior warning of the attacks in Mumbai but failed to act.
Over 170 people were killed in a series of coordinated attacks on the city.
Timeline of Mumbai attack
The Prime Minister Manmohan Singh has been leading an all-party meeting to discuss new measures against terrorism.
Earlier the country's Home Minister and National Security Advisor both tendered their resignations.
The Prime Minister announced that finance minister Palaniappan Chidambaram would replace Shivraj Patil as Home Minister.
The country's national security adviser M.K. Narayanan also offered his resignation.
Meanwhile, Pakistan has expressed concern about rising tensions with India, after allegations that gunmen who attacked the Indian city this week had Pakistani links.
The Indian government claims investigations reveal the involvement of groups based in Pakistan.
Pakistan's President Asif Ali Zardari has offered full co-operation with India in bringing those responsible for the attacks on a number of hotels.
His government denied any involvement in the violence but acknowledged that relations with India are under serious strain.
India has already boosted coastal security with the Indian Navy and the coast guard carrying out coordination patrols.
The Mumbai attackers are said to have come to the city by sea from the Pakistani port of Karachi, according to security officials.
They have said they were from the Lashkar-e-Taiba a Pakistan-based group that has been blamed for previous attacks in India.