The State Department yesterday released a rebuttal to criticisms of its white paper on El Salvador that were raised by articles in The Washington Post and The Wall Street Journal.

The new document denied that the original white paper contained significant errors, though it acknowledged numerous points raised in The Post and Journal articles.

The white paper, released last February, was the first significant initiative by the Reagan administration in the field of foreign affairs, and was used to help justify increased American aid to El Salvador. Earlier this month The Post and the Journal published articles questioning whether the captured documents on which the white paper was largely based actually supported its conclusions.

"Most of the criticisms . . . are either based on incorrect assumptions or are inaccurate," yesterday's rebuttal said. "The few points of misstated detail or ambiguous formulations that have been correctly identified [in the articles] do not in any way change the conclusions of the report. . . . The analysis and conclusions of the special report are soundly based and fully valid."

The State Department ignored many of the points raised in the newspaper articles and declined to explain why several key documents were altered in ways that bolstered the arguments in the white paper when they were translated from Spanish to English.

The department declined to give a briefing on the rebuttal it released yesterday, which meant reporters could not ask any questions about it or the original white paper. An official at the department said the rebuttal was released at 4 p.m. without ceremony to diminish any chance that it could get on the networks' evening news program last night. "We didn't want to put El Salvador back on the front pages," this official said.

Rep. Michael D. Barnes (D-Md.), chairman of the House Foreign Affairs subcommittee on inter-American affairs, yesterday issued a point-by-point commentary on the new rebuttal, concluding that it "clearly fails to lay to rest the doubts about the white paper."

The rebuttal does not mention or seek to defend the conclusion of the white paper that the insurgency in El Salvador has been "transformed into a textbook case of indirect armed aggression by communist powers through Cuba." Instead the rebuttal defends the conclusion that "Cuba and other communist and radical states have interfered directly in El Salvador."

The Post's article concluded that the white paper contained errors and misleading statements "that raise questions about the administration's interpretation of participation by communist countries in the Salvadoran civil war."

One section of the rebuttal disputes a phrase in The Post's article which said that one captured document cited in the white paper "was the only one that linked the Soviets directly to the Salvadoran civil war."

"This is simply not true," the rebuttal said, citing documents that mention two meetings (contents unknown) between Salvadoran rebels and Soviets, and also references in documents to the Soviet Union as a "strategic ally" of the insurgency which was fully committed to help the rebel cause.

The document referred to by The Post raised the possibility that the Soviets would actually transport arms to rebels. The Post article noted that the white paper left the impression that the Soviets did this, though the documents reveal only that a Salvadoran communist leader was enormously frustrated that the Russians refused to agree to transport the arms. The rebuttal did not address this point.

On another point the rebuttal acknowledges that some captured documents in the State Department's possession, but not cited in or released with the white paper, described the rebels' difficulties in acquiring enough arms. However, the rebuttal said, these documents "were from October 1980 and earlier." Documents dated "November 1980 and later reveal a dramatic change."

However, one document cited in The Post's article which suggested both that the rebels were short of arms and that they were planning operations that did not call for very many weapons was dated Nov. 18.

Acknowledging several errors in the white paper, the rebuttal says that misattributions of authorship of some documents or wrong descriptions of them in no way diminish their "validity" or findings based on them.