The U.N. Security Council has authorized the inspection of ships suspected of carrying highly prized charcoal from Somalia, a move aimed at enforcing a ban on charcoal exports and cutting off a lucrative source of funding for the Islamic extremist group al-Shabab.

The council approved the British-drafted resolution Friday by a vote of 13-0 with Russia and Jordan abstaining.

Britain's U.N. Ambassador Mark Lyall Grant said that since the council banned charcoal exports from Somalia in February 2012 the trade in charcoal from the Horn of Africa nation has actually increased.

He said U.N. experts monitoring sanctions on Somalia estimate that al-Shabab kept up to one-third of the $250 million annual charcoal trade.

The resolution also extends the mandate of the African Union force in Somalia until Nov. 30, 2015.