Former Maryland governor Marvin Mandel, until now on the defensive in the Great Furniture War, mounted his own attack today by suing the state of Maryland.

In a lawsuit filed here today, Mandel asserted that most of the furniture and bric-a-brac that state officials say he improperly carted away from the governor's mansion in 1977 was actually his property. Furthermore, Mandel contended, the state has 18 pieces of his personal property and he wants them back.

"I want what belongs to me," Mandel declared after he and his wife filed the suit in Anne Arundel County Circuit Court.

State officials, as they asserted they would last month, are preparing to file their own lawsuit Friday against Mandel and his wife, Jeanne, to regain more than 50 disputed items they say rightfully belong in Government House, the executive mansion from which Mandel moved after his political corruption conviction.

Today, Attorney General Stephen H. Sachs would comment only that, "Everything we have to say we'll say in our suit Friday. I promise you it will be highly relevant and completely responsive to today's allegations."

And so went the latest skirmish in a war tht already has involved a six-month investigation by state antitrust lawyers, a 327-page confidential report, hours of haggling between Sachs and Mandel's attorney, and a moving day last week when an orange van carted pieces of furniture from Mandel's home to the Old Maryland Armory.

The first shot was fired last month, when the state presented Mandel with a letter demanding the return of 87 pieces of furniture, ranging from a set of commemorative spoons to a regulation size pool table.

Sachs said the entire list of items was worth at least $35,000 at today's prices, and that all were improperly taken from the elegant Annapolis governor's mansion when the Mandels moved out in October 1977.

"Outrageous," replied Mandel. "It's no $35,000 involved. It's absoutely impossible."

But after days of haggling, the Mandels agreed to return 23 items, hired a moving van and sent most of them to a state armory for storage.

Today, in their lawsuit, the Mandels asserted that 39 of the remaining disputed items are, in fact, theirs. These include 13 pieces of redwood furniture, a Chippendale-style sofa and chair, a cooking pot, one brass ladle, 12 Kirk Repousse forks and 12 teaspoons. Furthermore, according to the lawsuit, the 12 matching Repousse knives were left at Government House and never returned to the Mandels.

Other items the state has demanded back, according to the lawsuit, "have not been and are not in the possession of" the Mandels.

The lawsuit also brings up 18 items never before mentioned in the long-running feud.

The Mandels assert that they own these items, which were left in the mansion for temporary storage at the time of their move, but have never been returned to them. These include a "governor's bust and pedestal," two amethyst vases, a train-track set, a Naughahyde sofa and chair and a brass box with flowers.

The Mandels have asked the court to declare the 39 disputed items theirs and to order the state to return the 18 other items.

Mandel said he has "spent enough time in court for a lifetime already," but believed that court is the only place this issue can be resolved.

The former governor was convicted on political corruption charges after two long federal trials, and is facing afour-year prison term unless the U.S. Supreme Court overturns his conviction.

"Some people think because of my circumstances, I'm just going to roll over and succumb," he said. "But I'm not gonna do it."