LIMA (Reuters) - Peru on Tuesday replaced its anti-drug czar, a lawyer who had criticized U.S.-backed eradication policies in the world's top coca grower and who had been one of the few progressives to survive a December Cabinet shakeup by President Ollanta Humala.

Ricardo Soberon, who previously worked for a legislator with close links to coca growers, was seen as a risky choice to lead anti-drug efforts in Peru, which experts say could surpass Colombia as the world's leading cocaine producer.

He will be replaced by psychologist Carmen Masias, according to a resolution published by the prime minister's office in Peru's official gazette. She has been subdirector of a government-run agency that works on drug abuse prevention and a board member of the Iberoamerican network working on drug dependency.

Soberon quit a month after an unexpected Cabinet shakeup in which Humala appointed fellow former army officer Oscar Valdes to be prime minister.

Humala carried out the changes to give his government a more law-and-order focus and clamp down on anti-mining protests. Critics said he purged leftists from his Cabinet who had supported him during last year's campaign and has drifted to the right.

Soberon suspended Peru's coca eradication efforts for a week in August as it evaluated existing anti-drug programs - surprising the United States, which provides about half of Peru's anti-drug money.

As a drug policy analyst he had criticized coca eradication programs funded by the United States as short-sighted, and advocated for more emphasis on helping farmers raise alternative crops like coffee and seizing chemicals used to refine cocaine.

He told Reuters in October that Peru was on track to eradicate its quota of 10,000 hectares (25,000 acres) of coca in 2011 but said he had also had some success in persuading U.S. officials to contribute more funding for alternative development initiatives rather than eradication.

But William Brownfield, the U.S. assistant secretary of state for international narcotics and law enforcement affairs, told reporters in November that the United States had only begun discussions on anti-narcotics funding with Peru's new government.

The U.S. Embassy in Lima did not immediately respond to request for comment on the appointment of Masias.

(Reporting By Caroline Stauffer; Editing by Terry Wade and Eric Beech)