The White House, in a move that has caused dismay at the Department of Energy, has ordered a new look at whether a $7 billion uranium enrichment plant under construction in Portsmouth, Ohio, should be terminated or delayed in view of "current congressional funding problems," it was learned yesterday.

Energy Department officials yesterday said they virtually had completed the new analysis, which was ordered by the White House only three weeks ago, and it "would continue to show a strong economic incentive to proceed" with the plant.

The review, ordered in a July 7 memorandum from presidential counselor Edwin Meese III to Energy Secretary James B. Edwards, follows a General Accounting Office report to Congress which concludes that building the new facility "is not justified" in view of the declining U.S. and world demand for uranium enrichment services.

Only a month ago, Assistant Energy Secretary Shelby T. Brewer told a Senate hearing the Portsmouth Gas Centrifuge Enrichment Plant still had the full backing of the Reagan administration.

The Energy Department has argued that the new facility, which uses the centrifuge enrichment process instead of the far more expensive gaseous diffusion process employed by the three existing government enrichment plants, is needed to enable the United States to remain a leading world supplier of nuclear fuel for atomic power stations.

Nevertheless, the fact that officials in the White House are questioning the new Portsmouth facility seems likely to fuel opposition in Congress, particularly in view of the GAO report and a Congressional Research Service study issued at about the same time questioning the need for the new plant.

The GAO suggested that the Department of Energy--which is developing an advanced isotope separation enrichment technology that could provide a much less costly way of enriching uranium--should continue using its existing plants until the new technique is ready.

Brewer contended, however, that the isotope separation technology "must reach a much higher stage of development before it can be counted on," and that in the meantime, the new Portsmouth facility offers the United States the opportunity to reduce the cost of enriching uranium and compete for new contracts.

Several Energy Department officials yesterday expressed contempt for the staff work in the memo, noting it also called for continued study of the possible transfer of the government's three existing uranium enrichment plants to the private sector--an idea generally viewed as a practical impossibility.

"Thank God the memo is only one page," one Energy Department official said.

No private companies in recent years have expressed any interest in purchasing the three existing enrichment plants--located at Portsmouth, Paducah, Ky., and Oak Ridge, Tenn.--which use massive amounts of electricity and are now regarded as uneconomical to operate commercially.

Beyond that, any proposal to sell these plants to private interests would certainly run into stiff opposition in Congress. In addition to producing low enriched uranium fuel for atomic power stations, the facilities also turn out more highly enriched uranium fuel for the U.S. Navy's nuclear submarines.

The Meese memorandum also instructed the Energy Department to analyze the possibility of government "incentives for getting the private sector to complete construction" of the new Portsmouth facility.

Sources voiced doubt any private company would now be interested in putting up the $6 billion needed to complete the plant by 1994, particularly since the construction work could be subject to Nuclear Regulatory Commission regulation.