Brent crude oil traded near a 12-year low in London Monday, briefly dipping below $28 a barrel, as the lifting of international sanctions on Iran paved the way for increased supply amid a global glut.

Futures fell 1.3 percent after earlier dropping as much as 4.4 percent in London to the lowest since November 2003. Iran is beginning efforts to boost output and exports by 500,000 barrels a day now that restrictions have ended, Amir Hossein Zamaninia, deputy oil minister for commerce and international affairs, said Sunday. Saudi Oil Minister Ali al-Naimi dismissed supply concern with a forecast that prices will recover.

Brent crude capped a third annual loss in 2015 as the Organization of Petroleum Exporting Countries effectively abandoned output limits. Iran, which was OPEC’s second-biggest producer before sanctions were intensified in 2012, is trying to regain its lost market share and doesn’t intend to pressure prices, officials from its petroleum ministry and national oil company said this month.

Brent on the London-based ICE Futures Europe exchange settled at $28.55.

West Texas Intermediate, the U.S. benchmark, fell as much as $1.06, or 3.6 percent, to $28.36 a barrel in electronic trading on the New York Mercantile Exchange, where the floor was closed for Martin Luther King Day. Trades will be booked Tuesday. The contract slid $1.78 on Friday. Prices have lost 21 percent this year.

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Buyers of Iranian crude are free to import as much of it as they want after the International Atomic Energy Agency determined that the country had curbed its ability to develop a nuclear weapon. As holder of the world’s fourth-largest reserves of crude and biggest deposits of natural gas, the nation gains immediate access to about $50 billion in frozen accounts overseas, funds the government says it will use to rebuild industries.