Over 500 Italian mayors launched a campaign on Wednesday to oppose a tax on second homes (IMU) recently adopted by Prime Minister Mario Monti's emergency government.

"The IMU tax will result in a net loss of 30 percent in municipalities' coffers," the leader of mayors' association ANCI Graziano Delrio told a press conference in Rome.

"This rigid and unfair tax will make municipalities and citizens poorer, it is actually a hidden capital levy imposed by the government," he added.

Also on Wednesday, Interior Minister Anna Maria Cancellieri called on mayors to be responsible.

"It needs a lot of attention and we will give it that. But the mayors, who are government officers, have institutional functions ... so concern for society and the needs of people is fine, but let's not forget that the mayors are representing institution," she said of the mayors' protest.

"I have every confidence in them and understand the difficulties, but they must maintain their sense of public duty," Cancellieri said.

Monti's cabinet of technocrats is facing tough opposition to his plans to liberalize the economy and reform labor laws in the crisis-hit country.

After adopting pension cuts and higher taxes, the government is currently trying to push through parliament a controversial labor reform package aimed at stimulating the stagnant economy.