Ali al-Naimi also said global refining capacity will remain a concern for the next four years, and called on consuming and producing nations to lift obstacles facing the industry.

"I believe oil prices during this decade will hold steady," al-Naimi said on Tuesday, but did not give a price range and said price movements are hard to predict.

"As for the kingdom's production, we are willing to increase it if there is a need and the new additions to production will be of light crude."

Oil held near $70 on Tuesday with US light crude up 15 cents at $69.92 a barrel and London Brent up 29 cents at $70.50.

Al-Naimi said earlier this month that oil prices above $70 per barrel were not in the interest of producers or consumers. US oil prices hit record levels above $75 a barrel last month, partially due to worries that Iran's row with Western nations over its nuclear programme could hit Tehran's exports.

Opec supplies about a third of the world's oil, but has been unable to depress oil prices. Saudi Arabia, Opec's largest producer, holds the lion's share of the cartel's spare capacity, but has repeatedly said there was no demand for extra barrels of its heavy crude which is more difficult to refine.

Declining margins

"We believe the concern for the industry in the next four years will be whether there will be adequate global refining capacity in view of the decrease in investments in the sector over the last two decades due to declining margins and strict government policy in main industrial countries and the big restrictions they impose," al-Naimi said.

"Despite the fact that there are several global projects to build new refineries or expand some existing refineries ... these projects take a long time to complete," he said.

The Saudi state oil firm, Aramco, planned to increase its refining capacity at home and abroad by two million barrels a day over the next five years, he said.