Internal Revenue Service agents have been warned to be extra when dealing with tax protesters, and to scout the terrain and look over their shoulders when meeting unknown informats in places where they could be "set up" for assasination.

Attacks and threats against IRS personnel have jumped in recent years at the IRS runs up against militant church and citizens groups. This column had copies of various in-house warnings to IRS personnel in different parts of the country. They were prompted by threats and assaults, and from information picked up by the IRS's CID (criminal investigation division) and its INS (Internal Security Division). The FBI is also working on threat investigations against federal personnel.

Officials say most of the information on the threats is classified. However, The Washington Post has obtained a document distributed to key IRS personnel in New England warning them of potential danger from a radical citizens group called Posse Comitatus. That group (the Latin name means "powder of a county") originated in the West, but now claims chapters in California, Colorado, New Mexico, Wisconsin, and on the East Coast.

The IRS warning to Boston regional employes says the agency has recently "learned that the posse Comitatus is allegedly planning to lure Revenue employes to isolated places and murder them. They have prepared a pamphlet," the warning bulletin says, "which describes a procedure whereby a phony address is used to lure the individual to a particular area and, while he/she is searching for the nonexistent address, the individual is 'eliminated' from a distance.

IRS rules encourage agents and other personnel to meet tax protesters at the office, whenever possible, and there are provisions for armed escorts in cases where employes have been threatened. A revenue service spokesman said the IRS takes the threats that have come from various antitax, anti-government interference groups "very seriously."

An IRS agent said employes in the field have gone to meet a tax-protester "and found themselves surrounded by dozens of people, in pickup trucks and all carrying pistols or shotguns."

An official said that the IRS, and various federal judges, have been targeted by militant groups who believe their organizations should be exempt from taxes, either because they are affiliated with church organizations or because they don't want any interference from the government -- and they consider taxes a major invasion of their privacy.