KABUL, Afghanistan — The Afghan government on Friday signed two contracts for the exploration of copper and gold deposits in the north, in a bid to move away from the country’s dependence on foreign aid by tapping its mineral wealth.

But watchdog groups say aspects of the contracts may violate the law and aggravate questionable practices that have marred the mining sector for years. Strongmen and political elites have long profited from the country’s riches, and mineral wealth could turn into another source of instability in a country mired in decades of war.

The contracts, which had been stalled for years, were signed in Washington between the Afghan ministers of finance and mining, and executives from Centar Ltd., an investment company founded by Ian Hannam, a former J.P. Morgan banker who partnered with local Afghan firms to bid for the mines.

Centar’s local partner is Sadat Naderi, who until June was Afghanistan’s minister of urban development. The Afghan minerals law prohibits senior officials from bidding on mining contracts for five years after they leave government.