After a day of violence targeted at north Indians in Mumbai and a few other places in Maharashtra, state authorities swung into action by arresting about 75 supporters of the Maharashtra Navnirman Sena and the Samajwadi Party.

"Police have arrested 25 people in Mumbai and around 50 people in neighbouring Thane," said chief minister Vilasrao Deshmukh, who was criticised by SP leaders for not taking prompt action on incidents of violence.

Meanwhile, sporadic incidents of violence were reported from parts of Mumbai and elsewhere, with MNS workers burning effigies of SP leaders and the latter retaliating by burning Raj Thackeray's effigies.

SP Mumbai unit chief Abu Asim Azmi met Deshmukh at Mantralaya and demanded that Raj be arrested for inciting violence.

Earlier on Monday, actor Amitabh Bachchan's residence was targeted by suspected MNS workers, in the backdrop of Raj Thackeray saying the actor was more inclined towards his home state Uttar Pradesh than Maharashtra.

Two unidentified persons hurled glass bottles in the direction of Bachchan's residence, forcing the police to set up high security cover at his residence. Amitabh has so far refrained from commenting on the issue.

MNS activists clashed with SP workers, attacked two theatres screening Bhojpuri films and assaulted north Indian taxi drivers and vendors.

With the Centre asking the state government to take proper steps to maintain law and order, Deshmukh said stern action would be taken against the guilty and there will be full protection for those living in Mumbai.

"Necessary action will be taken against those who attacked north Indians," Deshmukh told Congress MLAs and former ministers Kripashankar Singh and Naseem Khan at Mantralaya.

"People from other states should not be afraid. The state government will protect them and take stringent action against individuals and organisations seeking to hurt them," said Deshmukh, who earlier reviewed the security situation with senior police officials.

Samajwadi Party general secretary Amar Singh lodged an FIR against Raj Thackeray, accusing him of encouraging attacks on north Indians. Singh also petitioned the Election Commission, demanding that MNS be de-recognised and barred from contesting elections since its leader 'does not believe in Indian Constitution'.

On Sunday, MNS workers attacked several north Indian taxi drivers and street vendors. Many shops were forcibly shut down by the violent mob just before a rally, which was addressed by United National Progressive Alliance leaders, including Telugu Desam Party chief N Chandrababu Naidu [Images] and National Conference leader Farooq Abdullah.

Raj Thackeray's residence in Krishna Kunj building adjacent to Shivaji Park, venue of the UNPA rally, was on Monday a beehive of activity with hordes of MNS workers thronging the spot. Raj Thackeray, who made a brief appearance, however, declined to speak to waiting mediapersons.