(Dow Jones) The U.S. government Friday proposed regulations designed to enhance transparency for millions of workers covered by 401(k)s, pensions and other retirement plans, offering long-awaited guidance for investment firms.

Since the Pension Protection Act of 2006 was passed, potentially creating a market that would permit investment advisors to recommend their own funds, some firms have been awaiting further guidance.

One of new rules would ensure that workers receive unbiased advice about how to invest in their individual retirement accounts or 401(k) plans. If adopted, it would provide safeguards to prevent investment advisors from slanting advice for their own financial gain. It would also require that investment advisors disclose their fees, and that computer models used to offer advice be certified as objective and unbiased.

The Labor Department estimates that 2 million workers and 13 million IRA holders would benefit from this rule to the tune of $6 billion. It is accepting comments on the regulation until May 5.

A second rule, which goes into effect in April, will establish new guidelines on the disclosure of funding and other financial information to workers taking part in multi-employer retirement plans, which are collectively bargained by unions and groups of employers. The rule will ensure transparency by guaranteeing workers can better monitor the financial condition and day-to-day operations of their retirement investments, the Labor Department said.

U.S. Reps. George Miller (D., Calif.), chairman of the House Education and Labor Committee, and Rob Andrews (D., N.J.), chairman of the pensions subcommittee, welcomed the proposal, released as part of the White House Middle Class Task Force's year-end report. "We hope that this proposal will help to ensure that investment advice is based on what is best for a family's long-term retirement security, not the investment adviser's commissions," they said in a statement.

The rules were met with disappointment by the Securities Industry and Financial Markets Association, or Sifma, Wall Street's main lobbying group. The proposed regulation "will do little to expand Americans' access to investment advice," Elizabeth Varley, managing director of government affairs at Sifma, said in a statement. "Today's move by Labor will hurt participants and investors, not help."

Many in the mutual-fund industry are likely to comment on the proposal. The Investment Company Institute, the fund industry trade group, said Friday that it is "a long-time supporter of making investment advice more broadly available to 401(k) investors by allowing them to obtain advice from providers that they are familiar with, subject to strict fiduciary and disclosure conditions." The ICI said it plans to file "a detailed comment."

The new regulations have a few key differences from the final regulations presented by the Bush administration, which were eventually withdrawn, according to Jan Jacobson, director of retirement policy at the American Benefits Council, a trade group representing plan sponsors. Under the earlier provisions, advice could be given by an advisor affiliated in some way with some of the investments offered under the plan, using a fee-leveling or unbiased computer-model arrangement. In a fee-leveling arrangement, a firm offering advice must charge a single flat fee to participants, regardless of which investments are chosen.

The Bush proposal incorporated an exemption that permitted the fee-leveling requirement to apply only to an individual advisor's compensation. Under the rule proposed Friday, however, the company of the employee providing the investment advice isn't permitted to receive any compensation that would vary based on what the participant invests in, Jacobson said. That may mean that some companies would restructure so that they are able to offer advice through affiliates, she said.