NEW YORK — Four lawmakers sued the city today over its handling of the Occupy Wall Street protests, saying police conduct is so problematic that the force needs an outside monitor.

The city and police violated demonstrators’ free speech rights, used excessive force, arrested protesters on dubious charges and interfered with journalists’ and council members’ efforts to observe what was going on, the four city council members and others say in the federal civil rights suit.

“This unlawful conduct has been undertaken with the intention of obstructing, chilling, deterring and retaliating against (the) plaintiffs for engaging in constitutionally protected protest activity,” says the suit, which was filed a day before Occupy and labor activists planned a large May Day march.

The city Law Department did not immediately respond to a request for comment Monday. Mayor Michael Bloomberg has defended police handling of the protests.