The government moved yesterday to defuse charges that it has been obstructing the Progressive magazine's court fight to publish an article on the hydrogen bomb.

The charges were made by the American Civil Liberties Union as a result of the closing of the public library of the Los Alamos Scientific Laboratory in New Mexico for a review of the security classification of documents on file there.

The closing followed the discovery that a report on the open book shelves, which contained H-bomb data, had been copied by ACLU researcher Dimitri A. Rotow. The 23-year-old report, had been classified secret but, according to the Department of Energy, was declassified by mistake four years ago.

In a Wednesday letter to the Justice Department, the ACLU, acting as counsel to the Progressive's editors, pointed out that the purpose of Rotow's research was to confirm what Howrd Morland, writer of the article, had learned in the same library last year.

Alleging "official misconduct and interference with the preparation of our defense," ACLU legal director Bruce J. Ennis threatened to go to court to seek dismissal of the government case or other sanctions if the department didn't meet certain demands within 48 hours.

Late yesterday, Deputy Assistant Attorney General Thomas S. Martin agreed to take the steps necessary to assure the ACLU that the government was not destroying documents or taking other improper actions. In a letter to Ennis, Martin also said, "I deeply regret my inconvience caused by the classification review" at Las Alamos.

In New York City, the ACLU said it was "pleased" by the Martin letter. At the same time, however, a spokesperson said the organization was "certainly not happy" over a development in Chicago.

There, the 7th U.S. Circuit Court of Appeals rejected, 6 to 0, a motion by the ACLU, the Progressive, and Morland to expedite a hearing on their appeal from a two-month-old order by a federal judge suppressing publication of the article.

The appeals tribunal said it will hear argument in the case Sept. 10. The ACLU had proposed July 10.

The delay left ACLU executive director Ira Glaser "appalled," because, he said, it indicated a "casual" attitude toward the first prior restraint - by preliminary injunction - in the nation's history.

On Monday, ACLU lawyers will meet to plan responses to the 7th Circuit action and the Martin letter.

The Justice Department official said that DOE "has never contemplated the destruction of any documents nor have any been destroyed."

Rejecting the ACLU's assumption to the contrary, Martin nevertheless agreed to the organization's so-called "alternative demands."

In response to Ennis's letter, Martin said, the Justice Department has asked DOE "to instruct the DOE weapons libraries not to destroy any documents that have been in the public domain since the case was commenced."

In addition, Martin wrote, the Los Alamos library is keeping a detailed list of the documents that have been removed for the classification review. Defense counsel with the necessary security clearances will have access to the list, as well as to any relevant document.

Such actions should "dispel any misconception you may have concerning the classification review," Martin said.