ST. PAUL, Minn. (AP) _ A judge has ordered a spot check of confidential tobacco industry documents to see if the companies illegally used lawyer-client confidentiality to hide damaging research.

District Court Judge Kenneth Fitzpatrick said the spot check by a court-appointed master could lead to review of 150,000 of the industry's most sensitive documents.

The judge's ruling Friday was in response to a motion by Minnesota's attorney general seeking to force the release of additional documents.

State Attorney General Hubert Humphrey III and Blue Cross and Blue Shield of Minnesota are seeking the documents in their lawsuit against six cigarette makers. The 1994 lawsuit, which seeks to recover medical costs for treating smoking-related illnesses, alleges the cigarette makers defrauded consumers by hiding research linking smoking and health concerns.

``We have said from the onset that the tobacco industry has used law firms and lawyers to shield the evidence,'' Humphrey said. ``This decision is a monumental step at getting to the truth.''

Under law, attorneys can lose the lawyer-client privilege if it is used to conceal crime or fraud. The judge said the plaintiffs had presented enough evidence of wrongdoing to justify the spot check.

Fitzpatrick said the spot check would be conducted over 15 days in his chambers to determine if he should order a more extensive look at documents tobacco companies have claimed are confidential under the lawyer-client privilege.

One industry lawyer was stunned.

``I have never heard of a process like this,'' said Michael York, a Washington, D.C., attorney who represents Philip Morris. ``I frankly don't understand how it can be applied.''

Tom Gilde, an attorney representing Blue Cross, said the judge and special master will be looking at documents that no one outside the tobacco industry has seen before.

``This is a blow to the tobacco industry, to be sure,'' Gilde said.

The Minnesota lawsuit, one of 28 such legal actions filed by state attorneys general around the nation, is set for trial in January.

The cigarette makers are negotiating with attorneys general representing 26 of the states, including Minnesota. The companies are offering to pay at least $300 billion over 25 years, submit to some Food and Drug Administration regulation of their products and agree to advertising and marketing restrictions.