Russia has yet to deliver on the pledged cuts, while Saudi Arabia has cut its production far below the levels it had pledged, compensating for waker compliance by other OPEC states.
Rosneft said it came as a surprise to many observers that OPEC's compliance with cuts was more than 90 percent, and said the success was because the Saudi position on reducing production had "changed a great deal" from the past.
A recovery in U.S. oil output may deter OPEC and non-OPEC producers from extending production cuts beyond June and might lead to a new price war, Russia's top oil major said on Monday.
U.S. shale oil production had been in retreat as oil prices tumbled from above $100 a barrel in 2014 to below $30 in 2015, making costly fracking processes less profitable.
A deal by the Organization of the Petroleum Exporting Countries withRussia and other producers to rein in output by 1.8 million barrels per day (bpd) for six months from Jan. 1 lifted prices but also encouraged U.S. firms to boost supplies.
"It became evident that U.S. shale oil output has become and will remain a new global oil price regulator for the foreseeable future," Rosneft said in a written response to Reuters.