Odd-even gasoline purchase restrictions will end in the District of Columbia, Maryland and Virginia at midnight Sept. 30 unless gasoline lines form again before then, local officials announced yesterday.

However, no decision has been made to suspend minimum gasoline purchase requirements of $5 in Virginia and $5 and $7 (depending on car size) in the District and Maryland.

The decisions -- which indicate the area's steady but incomplete return to normal after the most recent crisis -- were made during a conference call yesterday including District Mayor Marion Barry, Maryland Gov. Harry Hughes and Virginia Gov. John N. Dalton.

Hughes aide George Liebmann called the decisions a "gradual and cautious approach" to deregulating gasoline sales in the area.

"We do not wish to convey the notion that the situation has so improved that people can disregard the problem," Liebmann said,

He said the supply of gasoline in Maryland is still 4 to 7 percent below this period a year ago.

Odd-even and minimum purchase restrictions were imposed in the Washington area June 21 after tight oil supplies worldwide and other factors had led to weeks of long gasoline lines here.

By early August, the lines had begun to disappear, and for the past several weeks the situation has appeared normal. However, service stations have continued to remain open fewer hours daily than before the crisis.

Many motorists and stations the last few weeks have ignored the odd-even and minimum purchase requirements.

"The thing is not being observed by motorists and no one's enforcing it and I'm afraid we'll need it again and people will have a very lax attitude [toward restrictions], said Vic Rasheed, executive director of the Greater Washington-Maryland Service Station Association.

Rasheed and others have said restrictions should have been lifted weeks ago.

However, some observers feel the restrictions should be continued.

Glenn Lashley, a spokesman for the American Automobile Association, said lifting the odd-even restriction would be premature.

"If people start unnecessary driving again we could be back in lines in October," Lashley said.

Under the plan, motorists with odd-numbered license plates may buy gasoline on odd-numbered days and those with even-numbered plates on even days.

The officials announced yesterday they will decide before Sept. 30 whether to lift the minimum purchase requirements as well as the odd-even restriction.

However, there was a feeling among officials yesterday that lifting both simultaneously would be a mistake.

"I tend to doubt [minimum purchase requirements] will be lifted because . . . many people felt this is some king of a check against topping off," said Paul Edwards, press aide to Dalton.

"None of us want to see a reversion back to the gasoline consumption patterns of the spring," said D.C. energy chief Chuck Clinton.

In the District the odd-even rule expires automatically Sept. 30 and action by the City Council would be required to continue it. In Maryland and Virginia, the rules last until they are rescinded by the governors.