WASHINGTON (AP) _ Federal regulators want airlines to get tough with unruly passengers.

The Federal Aviation Administration sent an advisory circular to airlines Thursday urging them to develop formal policies for dealing with the growing problem of passenger misconduct.

That should include a ``zero tolerance'' policy toward passenger misconduct, including encouraging employees to report problems and calling in law enforcement authorities when needed, the FAA said.

Federal rules prohibit passengers from assaulting, threatening, intimidating or interfering with airplane crew members.

In recent years, reports of problem passengers have increased, with several cases of planes being forced to land so police could take a passenger off.