OPEC Secretary General Mohammad Barkindo said that the production data for January in OPEC's most recent monthly report showed conformity from participating OPEC nations with agreed output curbs above 90 percent.
"All countries involved remain resolute in the determination to achieve a higher level of conformity," he said in a speech in London, according to a copy of the text.
The supply cut deal is helping to support oil prices, which at close to $57 a barrel are up from the low $30s a year ago, but still-rising U.S. inventories and expectations the OPEC cut will revive U.S. shale drilling have limited the rally.
Barkindo said that oil inventories were expected to decline this year.
"It was evident in the last quarter of 2016 that total OECD commercial oil stocks were falling, and it is expected that we will see a further drop during 2017," he said.
"We will continue to focus on the level of inventory drawdown to bring the level closer to the five-year industry average."