(Adds mining ministry's statement in paragraph 6th)

By Alonso Soto

QUITO, April 18 (Reuters) - Ecuador froze all mining exploration in the country on Friday and revoked hundreds of concessions, in a move that will increase the leftist government's control over natural resources.

The decision by the government-controlled assembly suspends exploration until a new mining law is approved aimed at boosting the state's share of revenue. It says the law must be approved within six months.

Ecuadorean President Rafael Correa wants to rework mining, oil and other deals to direct billions of dollars of revenue into state coffers to pay for increased social spending.

The government estimates the country holds $130 billion worth of metal deposits. Mining companies invest about $100 million per year in Ecuadorean exploration, industry officials say.

The wide-ranging decree could hamper the country's growing mining industry by delaying production plans and scaring away much-needed investment, analysts and company executives said. Share prices of Canadian miners operating in Ecuador plummeted sharply on Friday on news of the decree.

The mining ministry said in a statement that it would deliver the first draft of the mining law and project to build the state-run company on Monday. However, it said a final version of the law could be ready by late May.

Ecuador has no significant output of precious metals, but dozens of firms are exploring for copper and gold, including Canada's Aurelian Resources ARU.TO, Corriente Resources (CTQ.TO: Quote, Profile, Research) and IamGold Corp (IMG.TO: Quote, Profile, Research).