A weak crude oil market that's expected to last into 2016 should contribute to downward pressure on oil activity in North Dakota, a state regulator said.

The state reported 68 rigs actively exploring for or producing oil or natural gas as of Tuesday, one less than the previous day and down 65 percent from this date in 2014. That North Dakota Industrial Commission in its latest update said oil production in July, the last full month for which data are available, was 1.2 million barrels per day, a decline of about three quarters of a percent from the previous month.

More than 95 percent of the oil produced in the state comes from the Bakken and Three Forks shale region in the Williston basin in the west of the state. NDIC Director Lynn Helms said a weak crude oil market should throttle further developments.

"Rig count in the Williston Basin had stabilized, but the drop in oil price associated with anticipation of lifting sanctions on Iran and a weaker economy in China is leading to further cuts," he said in a statement.

Crude oil prices are down more than 50 percent from last year. Recent declines in the price per barrel were attributed to a slowdown in the Chinese economy and the expected return of Iranian crude oil to the international market. Low demand and extra supply explains the long-term trend in prices.

West Texas Intermediate, the U.S. benchmark for crude oil prices, is $44 per barrel, down about 2.5 percent from the start of the month.

"Oil price weakness, now anticipated to last well into next year, is the main reason for the continued slow-down," Helms said.

Gross domestic product in North Dakota increased 6.3 percent last year, beating out all other U.S. states. Gov. Jack Dalrymple said no single industry in the state was behind the growth trajectory.

For cities and counties in the oil-rich parts of the state, the slowdown could result in decreased revenues during the second half of 2015 and early 2016. Ratings firm Standards & Poor's in April said, however, the North Dakota economy will be able to cope with a depressed energy sector.