Nearly 30 members of the congressional committees overseeing oil and gas companies held personal assets in the industry totaling $9 million to $14.5 million late last year. That included at least $400,000 in the three companies at the heart of the Gulf of Mexico oil-drilling disaster, according to a Washington Post analysis of financial disclosure forms released Wednesday.

Among the members who owned the most oil industry stocks were Rep. Fred Upton (R-Mich.), who had nearly $100,000 invested in BP, and Sen. John F. Kerry (D-Mass.), who held as much as $650,000 in ConocoPhillips shares.

Wednesday was financial disclosure day on Capitol Hill, the one time of the year when government watchdogs and the media can glimpse the personal assets of Congress members. Lawmakers must show the value of their assets as of the previous Dec. 31, as well as any gifts they received and financial transactions they made. Federal laws do not require them to disclose exact amounts; they must show only where their assets fall within a broad range. Critics, including some members of Congress, have pushed for lawmakers to reveal their finances more regularly and in greater detail, to prevent conflicts of interest between their holdings and their legislative portfolios.

According to the disclosure forms, last year saw an increase in lawmakers investing in oil and gas firms. In 2008, members of the five committees held investments worth at least $8.1 million in companies they oversaw; by the end of 2009, that figure had grown by more than 12 percent.

Holdings in the companies involved in the April 20 Deepwater Horizon oil rig explosion in the Gulf of Mexico also grew last year, from a minimum of $98,000 to a minimum of almost $400,000. At the top end of the estimates, lawmakers on those panels may have held just shy of $1 million in shares of BP; Transocean, which owned the oil rig; and Anadarko Petroleum, a lease partner. The three companies are now under the microscope of those same lawmakers.

Before the gulf disaster, some lawmakers sold off shares in the companies now involved, including Kerry, whose wife, Teresa Heinz Kerry, sold the last remaining shares she held in Transocean. But at the end of 2009, Heinz family trusts still held $350,000 to $750,000 in BP stock, much of it bought last year. (Laws require members of Congress to disclose their spouses’ assets as well.)

House Minority Leader John A. Boehner (R-Ohio) also held as much $50,000 worth of stock in the British oil giant, which owns the well that has been spewing oil since the explosion off Louisiana.

Kerry -- the Senate Democrats’ lead negotiator on energy legislation -- had at least $6 million in assets from a dozen big oil and gas companies, including BP, Royal Dutch Shell, Exxon Mobil and ConocoPhillips. The senator said his wife’s inherited trusts, from her first husband’s family ketchup fortune, would not deter him from taking on the oil industry.

“Senator Kerry has been the Senate’s best environmental champion for more than 25 years and has written and urged legislation to end our dependence on foreign oil. Inherited holdings in family trusts he has no control over whatsoever clearly have no impact on his fight for a green economy and a clean environment,” Whitney Smith, Kerry’s spokeswoman, said in a statement.

Kerry sits on the Senate commerce committee, which oversees parts of the oil and energy industry along with the Energy and Natural Resources Committee and the Environment and Public Works Committee. In the House, most energy issues are overseen by the Energy and Commerce Committee and the Natural Resources Committee.

Upton, who owned $350,000 to $1 million worth of oil and gas holdings, is the largest such holder of shares in such firms among House members serving on the key committees. He is the top Republican on the commerce panel’s energy and environment subcommittee. Last year he bought stock in ConocoPhillips, Devon Energy, Occidental Petroleum and other companies, according to the disclosures.

An Upton spokesman did not respond to requests for comment.

Congressional leaders also have varied investments in the oil, gas and energy fields. The husband of House Speaker Nancy Pelosi (D-Calif.), one of the leading promoters of alternative energy, holds $50,000 to $100,000 in stock in Clean Energy Fuels, a company that bills itself as North America’s largest supplier of natural gas for automobiles.

“The speaker has been an advocate for increasing our country’s energy independence and for renewable energy for decades, long before this purchase,” said Drew Hammill, a spokesman for Pelosi.

Boehner, who once ran a plastics company in southern Ohio, diversified his holdings in 2009, buying $105,000 to $350,000 worth of oil and gas stocks that included BP. His office said the purchases would not affect his legislative actions.

“Late last year, Boehner closed out his retirement account from the small business he ran before coming to Congress, and, on the advice of his financial advisor, shifted the funds to other investments,” Mike Steel, Boehner’s spokesman, said in a statement.

Staff writers Dan Eggen, T.W. Farnam, Dan Keating and Ben Pershing and research editors Alice Crites and Madonna Lebling contributed to this report.