A consultant to the Consumer Federation of America yesterday scoffed at the notion that Congress might raise welfare benefits to shelter poor people from the impact of higher natural-gas prices if ceilings were removed.

A proposal to couple an increase in welfare benefits with decontrolling natural-gas prices is either fantastically naive "or it is utter cynicism," said Bob Eckhardt, a former Democratic congressman from Houston.

"If anyone at this time believes there is a great likelihood to put up an extra $5 billion for welfare, that person also believes in the Easter bunny and the tooth fairy," he said. Eckhardt is the CFA's energy consultant.

Eckhardt made his remarks during the first day of hearings in the House fossil and synthetic fuels subcommittee on problems in pricing and marketing natural gas.

The hearings are not focused on specific legislative proposals but are expected to lay groundwork for attempts next year to alter the schedule for lifting natural-gas price controls.

"Congress does not deal easily with natural-gas issues," subcommittee Chairman Philip R. Sharp (D-Ind.) noted at the outset. The Reagan administration, bowing to election-year realities, backed off earlier this year from a promised effort to eliminate controls.

At the hearing, the Council on Economic Development, a group of business and academic leaders, and the Conservation Foundation, an environmental group, called for removal of controls that would be tied to improved welfare benefits for the poor, who spend a larger percentage of their incomes on fuel than do middle-income families.

"We don't come to this as an afterthought. We don't offer it as a sop," said William K. Reilly of the Conservation Foundation. "We believe in one every bit as much as the other."

Reilly also said that the two groups consider it a price "worth paying" for complete decontrol if some kind of tax were levied on the "windfall" to companies that own large quantities of old gas. Old gas is under the most rigid controls under the Natural Gas Policy Act.

Richard J. Bryan, speaking for the Council of Industrial Boiler Owners, who are industrial users, said that his group supports orderly, phased removal of all wellhead price controls for natural gas.

"Industrial boiler owners believe that additional supplies of natural gas will be available, if wellhead prices are totally deregulated," he said.

Industrial users, who account for 40 percent of the market, generally support taking controls off prices. Some advocates for residential users had expected them to be an ally in favor of continuing controls.

"The reason they favor decontrol is because they would rather have a guaranteed supply," Rep. Daniel R. Coats (R-Ind.) said yesterday to someone expressing surprise at the industrial users' position.