TEHRAN (Reuters) - Iranian President Mahmoud Ahmadinejad told regional leaders on Wednesday that the capitalist system was close to collapse.

Opening a one-day summit of the 10-nation Economic Cooperation Organization (ECO) including Turkey, Pakistan and other neighbors, he also suggested a single currency should be used in trade between members.

After the collapse of the closed socialist economy, the capitalist economy is also on the verge of collapse, Ahmadinejad said in a speech.

The liberal economy and the free market have failed, he said, pointing to the use of thousands of billions of dollars to bail out Western banks and companies.

Like other big oil producers, Iran is facing falling revenue after crude prices plunged about $100 a barrel from a peak of $147 in July, hurting its main source of income. It is also struggling with double-digit inflation.

Iran, Turkey and Pakistan are the founding members of ECO, which was set up in 1985 and now includes seven other regional nations, Afghanistan among them.

The Tehran meeting is expected to discuss ways to boost trade and economic cooperation in a region which boasts major energy resources.

Ahmadinejad made a series of recommendations, including currency cooperation.

The process of obtaining one single currency in the trade and exchanges among members, and in the next stages with other countries and neighbors, should be designed, he said.

CRISIS INTO OPPORTUNITIES

Turkish President Abdullah Gul said he believed regional countries had the potential to turn the economic crisis into opportunities, with its natural and other resources.

He called for a lowering of regional customs tariffs to boost trade and increased transport and energy cooperation.

Afghan President Hamid Karzai said the narcotics trade was hurting Afghanistan's economic and social development and asked ECO to help in fighting the problem.

Afghanistan, which produces 93 percent of the world's heroin, has been ravaged by decades of civil war and a U.S.-led international coalition is currently battling Islamist Taliban insurgency in the Central Asian state.

Analysts say combating drugs is one area where Iran, which shares a long border with Afghanistan, share an interest with its old foe the United States.

In a swift overture toward Tehran, the new U.S. administration of President Barack Obama last week said it would invite Iran to a meeting later this month to discuss Afghanistan. Iran has said it would consider the request.

(Writing by Fredrik Dahl; Editing by Angus MacSwan)

Pakistan Afghanistan