Federal Reserve Chairman Ben S. Bernanke cautiously stepped into the debate over the tax treatment of high-flying private equity firms and hedge funds this week.

In appearances before both House and Senate committees, Bernanke was repeatedly queried by lawmakers eager to get the country’s top economic voice on record about whether to alter how the private investment funds are taxed.

Bernanke avoided taking a specific stance on legislative proposals but did caution lawmakers Thursday that raising the taxes paid by fund managers could drive them overseas.

“It might not affect their activities, but it might affect their locations,” Bernanke told members of the Senate Banking, Housing and Urban Affairs Committee.

His comment came in response to a question from Charles E. Schumer, a New York Democrat, who asked Bernanke “theoretically” what would happen if lawmakers change tax laws for the funds and their managers.

Bernanke appeared before the panel to present the Fed’s semi-annual monetary policy report to Congress.

Schumer, who counts Wall Street and its denizens as key constituents, voiced concern that proposed changes would hurt New York’s role as a global financial center.

In recent weeks, lawmakers have been debating whether the private investment firms and their fund managers are paying appropriate taxes.

A broad House proposal and a more limited Senate measure (HR 2834, S 1624) would result in significantly higher tax rates for fund managers and any hedge fund or private equity firm that chooses to trade its shares publicly.

Proponents of the legislation have framed the debate as an issue of tax fairness.

Speaking just minutes after Schumer, Indiana Democrat Evan Bayh asked Bernanke how he would explain to a crowd of middle-class constituents that some of the wealthiest Americans are taxed at a rate of 15 percent, as opposed to the higher levels paid by most workers because their earnings do not qualify as capital gains.

Bernanke ducked the question, noting that economists long have argued over the merits of taxing capital income at a lower rate than normal income.

Still, Bernanke’s responses over his two days of testimony indicated a wariness about inhibiting private investment funds. Answering questions from members of the House Financial Services Committee on June 18, Bernanke spoke about the “important benefits” of hedge funds and private pools of capital.

“They provide a good deal of liquidity in the markets and help the markets work more efficiently,” he said. “In private equity, in particular, they play an important role in the market for corporate control.”

On another issue, Bernanke said he was “concerned” about language in a House-passed bill (HR 1427) that would overhaul regulation of Fannie Mae and Freddie Mac, the housing finance giants.

In response to Alabama’s Richard C. Shelby, the ranking Republican on the Senate Banking panel, Bernanke raised questions about a provision dealing with the ability of the firms’ regulator to assess the risks posed by their massive investment portfolios. Bernanke has raised concerns that the combined portfolios of the two companies, which total around $1.5 trillion, pose a risk to the economy.

Shelby and others have argued that the regulator should be able to force the companies to reduce the size of the portfolios if they pose a risk to the broader economy. The House language would allow the regulator only to consider the risk posed to the companies.

Banking panel members are working to draft their own version of the legislation.

After the hearing, Christopher J. Dodd, D-Conn., who chairs the Senate panel, said that it would likely take up legislation this fall.