In a letter to the Internal Revenue Service Tuesday, a representative from Yale’s unions requested that the agency investigate Yale’s investment disclosure policies.

Antony Dugdale, research analyst for Local 34, sent the letter on behalf of the federation representing Yale’s unions. The letter requested that Yale return to its old policy of including the business addresses of its subsidiary organizations on the 990 form it must yearly with the IRS. Previously, Yale had included the addresses of the subsidiaries on the form. But in this summer’s form, the addresses were replaced with a Yale post office box address.

Yale must file the form to maintain its status as a not-for-profit corporation.

Yale spokesman Thomas Conroy said he was not familiar with the issue and declined to comment.

In the letter, Dugdale wrote that failure to disclose addresses makes it difficult to determine how Yale’s assets are being used.

Dugdale said the unions are particularly concerned about the management of Yale’s pension fund.

“Yale manages a $500 million pension fund on our behalf and an increasingly large amount of this is invested in private equity,” Dugdale said.

Dugdale said the private equity allocations make the exact value of the pension fund uncertain. He said the matter regards tax filings and is therefore under IRS jurisdiction. But he said IRS policies with regard to this issue are unclear.

“This is an unclear part of the IRS regulations and the IRS needs to issue the rulings,” Dugdale said. “So I expect the IRS to investigate this.”

The unions originally sent a letter to Connecticut State Attorney General Richard Blumenthal requesting that he investigate Yale’s disclosure practices. Blumenthal sent a letter Oct. 11 to Yale General Counsel Dorothy Robinson requesting Yale’s compliance with the unions’ request.

“I encourage Yale to meet the Federation’s request that Yale voluntarily disclose the principal business address of these entities to the extent that the addresses differ from those listed on Yale’s federal tax form,” Blumenthal said in the letter.

Blumenthal could not be reached for comment Tuesday.

Dugdale said the unions were pleased with Blumenthal’s support.

“It’s great to have the state attorney general’s support and to have him agreeing that Yale should uphold the highest standards,” Dugdale said.

Robinson was not available for comment Tuesday.

Blumenthal wrote in the letter that in the age of “repeated revelations of corporate scandals,” institutions like Yale should make an effort to disclose as much investment information as possible.

Union leaders said Yale investments are a particularly important issue for the unions, Local 34 President Laura Smith said.

Locals 34 and 35 represent nearly 4,000 clerical, technical, service and maintenance workers. Locals 34 and 35 are currently negotiating new contracts with the University.

In early November, the University denied the unions’ request for immediate representation on the Advisory Committee on Investor Responsibility and Yale’s Investment Committee.

Yale’s unions have previously asked that Yale disclose more information about its investments. The previous requests have often focused on investment ethics regarding the environment and social responsibility.

The unions’ request follows a recent announcement by the University of Texas of a policy of “maximum disclosure.” A state judge issued a preliminary ruling that the California Public Employees’ Retirement System must disclose information on the fund’s private equity performance.