Democrats on a House committee are seeking detailed financial records from dozens of large insurance companies, officials disclosed on Tuesday, part of an investigation into “executive compensation and other business practices” in an industry opposed to President Barack Obama’s plan to overhaul health care.

The request included records relating to compensation of highly paid employees, documents relating to companies’ premium income and claims payments, and information on expenses stemming from any event held outside company facilities in the past 2-1/2 years.

The requests were made in letters signed by Rep. Henry Waxman of California, who guided a portion of health care legislation through the House Energy and Commerce Committee last month as chairman, and Rep. Bart Stupak of Michigan, who heads the Energy and Commerce investigations and oversight subcommittee.

They wrote that the committee was “examining executive compensation and other business practices in the health insurance industry.” The Associated Press obtained a copy.

The requests were issued at a time when Mr. Obama’s health care proposal is under intense attack from Republicans and other critics, including the health insurance industry. Much of the opposition focuses on proposals for the government to sell insurance in competition with private carriers.

Mr. Obama and other supporters of a so-called government option argue it would help control costs and keep insurance companies honest by forcing them to grapple with competition.

Opponents say it gradually would undermine the present insurance structure, which is built around private insurers, and lead to a system controlled by the government.

The issue drew intense focus over the weekend, after Mr. Obama speculated aloud about the possibility that legislation might omit the government role in selling insurance.

The White House said there had been no change in position. But liberals, in particular, expressed dismay, giving rise to increased speculation that Senate Democrats could soon abandon all talk of bipartisanship and draft legislation tailored to their own rank and file. Any such measure would inevitably jettison many of the compromises crafted in weeks of bipartisan Senate talks, and it was unclear whether the talk was a ploy to persuade Senate Republicans to agree to a compromise.

A spokesman for the insurance industry declined to comment on the letter sent by Waxman and Stupak.

Nick Choate, a spokesman for Stupak, said 52 letters were sent late Monday to the nation’s largest health insurers, those with $2 billion or more in annual premiums. He said letters were not sent to other industry groups, some of which have been airing television advertising in support of Obama’s call for legislation.

The letter from Mr. Waxman and Mr. Stupak requested the information be provided by early September. While companies are not under legal obligation to comply, the committee could respond to a refusal by voting to subpoena the information at a later date.

Among the documents requested were records relating to compensation paid to any company executive earning more than $500,000 in any year from 2003 to 2008.

Mr. Waxman and Mr. Stupak also sought documents relating to premiums paid by policy holders, claims payments, sales expenses, administrative expenses and profits.