House members, prohibited from sending more than three mass-mailed newsletters a year to households in their districts, tripled their spending in the most recent three months for more costly first-class, individually addressed mailings to constituents, according to a report by the U.S. Postal Service.

Spending in the three months ending June 30 on third-class "franked" mailings by House members dropped 11 percent from the previous quarter, while the cost of first-class letters sent by House members rose by almost 33 percent.

During the last three months, House members sent 94.4 million bulk-rate pieces costing $9.6 million and 17.1 million first-class pieces costing $4.3 million.

The Postal Service report comes at a time when first-class mailings have become a major sticking point in House negotiations over new requirements to limit the amount a member could spend on mailings and to require public reports on such spendings.

"Some members who make very aggressive use of targeted direct {franked} mail are fearful of what Vic {Rep. Vic Fazio (D-Calif.)} is doing," said a Democratic member who sat in on discussions about the franking provision.

"Once a member and his staff turn from a newsletter to a personal format letter," a Republican member said yesterday, "they find it hard to go back. The computer makes it easier to produce than a glitzy newsletter."

Under current law and House rules, members can spend as much as they want on franked mail without reporting their actions. They are only required to file copies of materials, such as newsletters, that are mass-mailed -- defined as a single piece sent at one time to more than 500 addressees.

"It's a secret who is doing first-class mailing," the Democratic member said.

Fazio, chairman of the House Appropriations subcommittee on the legislative branch, is trying to work out an acceptable amendment on franking to prevent the House from running up future deficits, such as the $35 million it expects to pay for excess mailings this election year. Without a system to limit future spending, Fazio fears he will not get House approval for paying the mail deficit this year or the $59 million proposed for spending on official mail next year.

Fazio and others say they believe members would stay within their allocations and avoid another House deficit if there were a system of limits and public reporting on franked mailing. The Senate, which has such a system, is expected to spend $7 million less than the $24 million appropriated this fiscal year, according to the most recent Postal Service report.