Stepping up his campaign for Marathi signboards, MNS chief Raj Thackeray on Wednesday warned shop owners, not putting up the boards by Thursday, to face the wrath of his men and asked police in Mumbai to think before lathi-charging his party workers.

Raj said he has written a letter to the police, asking them to "think twice" before lathi-charging MNS activists involved in the agitation to enforce the civic body's deadline stipulating Marathi signboards on the city shops by August 28.

Addressing the party workers at Ravindra Natya Mandir in central Mumbai, Raj, whose two-year old party has been having regular confrontation with law-enforcement agencies over the outfit's strident anti-north India stance, said, "most of the shop owners have complied with the signboards deadline."

"However, there are some shop owners who are deliberately raising the bogey of oppression and coercion by MNS activists," Raj said, naming Viren Shah, owner of a leading garment store in Mumbai.

"Maharashtra's police, barring a few 'bhaiyya' (north Indian) IPS officers, are Marathi and are aware of the attempts to destroy Marathi," Raj said.

Despite Bombay Municipal Corporation's directive to put up Marathi signboards on shops, these people defy the directive, he said.

"They don't let out houses to Marathi people, insult Maharashtra and treat Marathi as the language of their servants," the MNS chief said.

A misconception has been spread that the MNS is raising the issue of Marathi signboards for electoral gains, Raj said.

"Our agitation is for Marathi pride and we are ready to keep away from elections if needed," he said. "The MNS workers are educated youths who are fighting for a just cause," Raj said in his letter addressed to police.

He asked his party workers to ensure that the letter reaches all police officials, police stations and police housing societies.

Appealing to police to spare a thought for the reason behind MNS members' involvement in the agitation, Raj said "My workers have taken to the street to fight your cause."