WASHINGTON (AP) _ The union representing IRS workers says tax collection agents are subject to increasing threats and wants more security for them in the next work contract.

One proposal advanced by the National Treasury Employees Union would set specific rules to let IRS agents request armed guards or law enforcement officials to help them deal with taxpayers considered dangerous.

``Without question, the number of taxpayers who are hostile and who have exhibited hostility toward the Internal Revenue Service, violent hostility, has been growing,'' Robert Tobias, the union's president, said Monday.

In the last five years, there were 3,200 reported threats and assaults on IRS workers, according to the Treasury Department. The IRS has come under criticism in recent years for poor customer service and allegations some agents harassed innocent taxpayers.

The union, which represents most of the IRS' 103,000 workers, is bargaining a new labor contract with the agency.