The Kenyan government has revoked all prospecting and mining licences granted during the first five months of this year after complaints about the issuing process.
The commissioner of mines has been suspended. Royalties on minerals have been raised.
The BBC reports Kenya has proven deposits of titanium, gold and coal. New deposits of copper and niobium have also recently been discovered.
Mining minister Najib Balala said on Monday the licences in question had been issued in a hurry and without transparency.
"We want to ensure the country gains from the mineral potential," he said.
"Any licence issued between 14 January - 15 May is hereby revoked immediately as we review each case to determine their nature and benefit to the country."
Earlier this year, the government promised to review laws regulating the sector, which currently includes more than 300 domestic and foreign firms either searching for minerals or in small scale production.
The BBC reports the IMF last week expressed concern over the new contracts, saying they were shrouded in secrecy.