Retirement plan administrators would have to disclose all fees deducted from investors’ 401(k) accounts under legislation backed by a U.S. House of Representatives panel.

The House Health, Employment, Labor and Pensions Subcommittee approved the bill today, which would require the Labor Department to impose penalties on plan providers who don’t disclose their administrative, investment management and transaction fees. The bill must be approved by the full House and Senate and signed by the president before taking effect.

“American consumers ought to know what they are paying in fees, and what those fees are going for,” said Representative Rob Andrews, a New Jersey Democrat, and a sponsor of the bill.

The House Education and Labor Committee, led by Representative George Miller of California, has been pushing for disclosure of 401(k) fees and more transparent marketing of retirement products. Earlier this year, Miller said that the savings plans don’t provide sufficient retirement security for many Americans and must be revamped.

The bill, which now faces a vote in the full House Education and Labor Committee, requires that all fees taken from a 401(k) account be disclosed in one number. Workers could request more detailed fee information from their plan administrator. Service providers are also required to disclose any financial relationship or potential conflicts of interest to plan sponsors.

Plans that seek limited employer liability must include at least one index fund in its investment line-up, on the grounds that they are less expensive and generally outperform actively managed funds, according to the legislation.

Republican opponents of the measure said they disagree with the increased regulation of investors. The bill “puts Washington in the position of dictating one business model over another,” said Representative John Kline of Minnesota.

Investors had $2.7 trillion in 401(k) accounts as of Sept. 30, according to the Washington-based Investment Company Institute, which represents mutual funds. The Congressional Budget Office estimated that workers lost $2 trillion over 15 months from declining stock markets since October 2007.

About 55 million private-sector employees have so-called defined-contribution retirement plans, where workers are responsible for managing their own funds, according to the Center for Retirement Research in Boston.

Republicans have sought to shore up Americans’ retirement savings by reducing Social Security income penalties for those who claim benefits before full retirement age, and providing tax cuts for investors and seniors.