WASHINGTON, July 18 — For six years, Vice President Dick Cheney has guarded the secrecy of the discussions and participants in his energy task force, which produced a report in May 2001 calling for accelerated development of domestic oil and gas supplies to deal with the nation’s energy needs.

Now, thanks to an unidentified former White House official who provided The Washington Post a partial list of individuals, companies and groups that met with the task force, it is possible to identify with greater precision who may have influenced its deliberations.

The list bears the names, The Post reported Wednesday, of nearly 300 people and organizations that met with the vice president or his staff during the months that the task force was preparing its report. It is not, however, the complete accounting that Congress and some environmental groups have demanded.

It has long been known that the oil industry was well represented at the task force meetings and found a receptive audience in Mr. Cheney, who had spent five years as chief executive of Halliburton, a leading oil-field-services company. He was given the energy assignment by President Bush, who himself had had a career in the oil business.