INTERVIEW-Iran committed to Afghan drug fight, UN says

* Iran, Afghanistan, Pakistan start joint anti-drug raids

* Iran committed to regional drug fight, U.N. official says

By Daniel Flynn

TRIESTE, Italy, June 27 (Reuters) - Iran is committed to a regional effort to tackle drug trafficking from Afghanistan and has begun joint counter-narcotics operations with Afghan and Pakistani authorities, a senior United Nations official said.

Iran, which has seen demonstrations after contested presidential elections earlier this month, declined an invitation to an international conference hosted by Italy on Saturday aimed at promoting stability in Afghanistan.

But Antonio Maria Costa, head of the United Nations Office of Drugs and Crime, said Tehran was taking steps to tackle the flow of heroin from its eastern neighbour, which has left Iran with the highest rate of drug addiction in the world.

"Most certainly the Iranian government is strongly committed to a regional effort," he told Reuters in an interview. "In recent weeks, we have seen tripartite drug interception. This is very new, it has not happened in the past."

Afghanistan, immersed in conflict since the 2001 invasion to topple the Taliban, produces more than 90 percent of the world's supply of opium, a thick paste from poppy that is then processed to make heroin and smuggled abroad.