More than 40,000 police were deployed in Mumbai and thousands of others formed self-protection militias as the city began a festival to the elephant-headed god Ganesha, six days after the bombings which left 52 dead.

In New Delhi, police Saturday shot dead two men they said were planning to attack a crowded place with a consignment of arms, including at least 10 hand grenades, seized three hours earlier during a search of a fruit truck.

A senior police official said the operation was carried out on "specific information" but warned that more Islamic militants were likely at large in the capital of 14 million people.

Police said they learned of plans for an attack in New Delhi after questioning the passengers of the fruit truck, which was registered in insurgency-wracked Indian Kashmir, and set up a police roadblock in a largely Muslim area of the city, Nizamuddin.

Police declined to comment on a report in the Hindustan Times newspaper that the plot was uncovered when a businessman overheard a telephone conversation saying 11 men had entered New Delhi ready "to do something bigger than Monday's blasts in Mumbai."

Police alleged at least one of the slain men was a Pakistani and that they belonged to Jaish-e-Mohammad, one of the most extreme groups fighting Indian rule in Kashmir.

Five people have been arrested in connection with the Mumbai attacks and many more questioned as police look for the mastermind, said Kripashankar Singh, home minister of Maharashtra province of which Mumbai is the capital.

PTI adds: Delhi Police personnel on Sunday arrested two Jaish-e-Mohammad terrorists from Bulandshahr district of Uttar Pradesh.

The arrested persons are brothers of one JeM terrorist Habibullah shot dead by police in an encounter in the national capital on Saturday night, they said.