NEWARK, N.J. (AP) _ Mobil Oil Corp. abruptly gave up its fight this week to keep sealed confidential environmental reports sought by a fired employee who is suing the company.

Mobil said it dropped its appeal of an unsealing order to speed the 2-year- old case along, and to put to rest what it called ''recent unjustified speculation'' in the media that it was trying to hide wrongdoing.

The papers themselves, several dozen environmental assessment reports on Mobil's chemical plants and attorney comments about them, shed little new light on arguments already made by attorneys for the dismissed employee, Valcar Bowman Jr. of Riverdale, Ga.

Bowman, then based in Princeton, was fired in April 1986 as Mobil Chemical Co.'s No. 2 environmental official. Mobil said he was fired in an economic cutback. Bowman, 47, says it was because he refused to go along with a cover- up of environmental problems - an allegation Mobil denies.

Mobil opposed an effort by attorneys for Bowman and The Associated Press - which U.S. District Judge Harold A. Ackerman allowed to enter the case - to have the docuents unsealed. He unsealed the papers, and Mobil appealed to the 3rd U.S. Circuit Court of Appeals. The company withdrew that appeal Thursday.

Company attorney Ron Neill said Mobil fought as hard as it to uphold the principle behind the Environmental Protection Agency's policy of critical self-assessment, in which industries police themselves when regulators can't.

''If these documents aren't afforded some privacy, people ... are going to be disinclined to do them if the local newspaper is going to splash them on the front page,'' said Neill. ''It was public interest.''

The promise of secrecy was used as an incentive to recruit companies to make such reports, said Lee M. Thomas, who was EPA administrator when the policy was set forth in the mid-80s.

But when news reports about Bowman's case and the struggle over the documents' disclosure came to light, Mobil's need ''to defuse the myth that we were trying to conceal something'' held sway, Neill said.

To First Amendment lawyers, it was an important victory.

If Mobil won, it ''would have created a new class of evidence shielded from public scrutiny,'' said Thomas Cafferty, an attorney for the New Jersey Press Association.

''This is a very limited and discreet intrusion'' into the self-critical process, he said. A court decision allowing the documents to be kept sealed, he said, would have been a serious departure from the principle that ''evidence introduced in a public court proceeding is part of the public domain.''

Thomas said such reports should be released only in ''tightly controlled situations.''

''This may be one of them,'' he said, but added he couldn't tell if their release in the Mobil case would have a chilling effect.

As for the papers themselves, they don't go much beyond excerpts contained in Bowman's court briefs, which have been reported on previously.

The briefs quote a Mobil attorney's memo spotlighting ''admissions of non- compliance'' of environmental regulations and how Mobil executives could be subjected to potential legal action if they knew about them.