Police and security forces in Mumbai were on high alert on Sunday after deadly bomb blasts in the Indian capital New Delhi, as huge crowds were expected for the final day of an annual Hindu festival.
About 45,000 police, intelligence officers and volunteers will be on the streets to ensure the popular Ganesha celebrations pass off peacefully, the head of Mumbai's anti-terrorism squad, Hemant Karkare, said.
"Maximum security has been deployed. We are fully prepared and we have been briefed them to be on the look-out for suspicious packages," he told AFP by telephone.
The security operation had been described as the most comprehensive the city had seen for the yearly ritual even before Saturday night's blasts in the Indian capital, that killed 20 people and left nearly 100 others injured.
Worshippers bringing their colourfully-painted idols of the elephant-headed god Ganesha to Mumbai's beaches for them to be ritually immersed will be subject to searches and also filmed by police for the first time.
Road closures and diversions have also been put in place while there will be a strong police presence in predominantly Muslim areas to prevent clashes.
Mumbai has come under fresh scrutiny after an email claiming responsibility for the co-ordinated attacks was traced to an electronics firm in the city's eastern suburbs.
Police are investigating whether the company's wireless network was hacked.
The militant Islamic group claiming Saturday's attacks, Indian Mujahideen, allegedly hijacked Internet connections in Mumbai to send emails before bombings in Ahmedabad and Bangalore in July.
Karkare refused to confirm or deny television news reports late Saturday that the message said Mumbai would be the next target.
"Mumbai is always a target because it's a commercial capital. In the past we have received such alerts. We are at a maximum state of readiness," he said.
The city was last rocked by a major attack in 2006, when a series of bombs exploded on its suburban rail network, killing more than 200 people and injuring hundreds more. The attack was also blamed on Islamic militants.