A news report published Wednesday says Afghanistan's minister of mines is accused of accepting an approximately $30 million bribe.

Afghan Minister for Mines, Mohammad Ibrahim Adel (2008 File photo)
The Washington Post newspaper says Mohammad Ibrahim Adel accepted the money in exchange for awarding a lucrative copper mining contract to a Chinese firm. The newspaper quotes an unnamed U.S. official as saying there is a "high degree of certainty" that Adel received the payment in late 2007, during the time when the state-run China Metallurgical Group won the multibillion dollar contract.

Adel denies the allegations.

The Chinese firm is expected to invest nearly $3 billion, and pay the Afghan government royalties of some $400 million per year, to tap into one of the world's largest unexploited copper deposits. When the contract was awarded in 2007, Adel hailed the deal as one of the biggest foreign investment projects in Afghanistan's history.  

The Chinese firm beat out challengers from countries including the United States and Canada who were also interested in the rights to extract copper from the Aynak deposit in central Logar province.

At least two U.S. officials have previously raised concerns that the bidding process may have been handled improperly.

James Yeager - a geologist who advised Afghanistan's mines minister - and former U.S. Congressman Don Ritter have both said they thought the bidding process was flawed.

On Tuesday, a Berlin-based group ranked Afghanistan as one of the world's most corrupt countries. The Transparency International group gave Afghanistan the second-lowest score in its annual perception rating of corruption. Somalia was the lowest.

Afghan President Hamid Karzai has been under increased international pressure to fight corruption in his government. On Monday, his government announced it would form an anti-corruption unit.