By Ramin Mostafavi

TEHRAN (Reuters) - Iran's cinema owners have threatened to close their movie houses to protest against costs that have soared since energy subsidies were slashed last year, sending a highly visible message of opposition to the government's key economic policy.

Despite restrictions on foreign films, often banned for reasons of morality, movie-going is hugely popular in Iran which has a lively domestic film industry, but the cinemas say rising costs are driving them out of business.

"After the implementation of the (subsidy) plan, the price of electricity, water and gas increased by 10 to 15 times, while the income of the cinemas did not increase," Habib Kavoush, a spokesman for the Cinema Guild told Sharq, a reformist newspaper, on Tuesday.

"Cinema owners have announced that if one cinema is forced to close due to its water and electricity bills we will shut down all the others," said Kavoush. An official at the cinema owners' association confirmed the industry's position.

The complaint is likely to strike a chord with Iranians who have seen their own utility bills soar after the government last December started slashing the $100 billion of annual subsidies that had kept prices of fuel and food artificially low for decades.

Gasoline prices rose as much as seven-fold overnight and the price of basic foods have jumped, with bread more than doubling in price.

The International Monetary Fund welcomed the reform that President Mahmoud Ahmadinejad called "the biggest economic plan in the past 50 years." Along with new cash payments to help people cope with soaring prices, it would lead to a fairer, less wasteful and richer Iran, he said.

Despite steadily rising inflation, which the IMF has forecast at 22 percent this year, there has so far been no public unrest over the subsidy cuts so any action by the cinemas would be particularly noticeable.

But the Ministry of Culture and Islamic Guidance said cinema owners were exaggerating the problem and said the government would help.

"The issue is not so critical ... no cinema will be closed due to this," ministry official Alireza Sajadpour told Sharq. "There is a plan to support the cinemas and it will be put into practice by maximum next 10 days."

Sajadpour told Iran daily it had been a bumper year for the movies, with several Iranian films taking more than several millions of dollars in the domestic market, including "Nader and Simin - a Separation," the Berlin film festival winner which Iran has entered for the Oscars.

(Writing by Ramin Mostafavi and Robin Pomeroy, editing by Paul Casciato)