L'AQUILA - The G8 world powers issued a joint declaration expressing "serious concern" Wednesday over post-election violence in Iran but said they were determined to find a peaceful resolution to the standoff over Tehran's nuclear programme.

"G8 countries continued to be seriously concerned about recent events in Iran," said the statement.

"Interference with media, unjustified detentions of journalists and recent arrests of foreign nationals are unacceptable," it added.

The declaration urged the regime in Tehran to hold dialogue with the International Atomic Energy Agency, the UN's nuclear watchdog, to resolve the long-running dispute over the scale of its nuclear ambitions.

"We strongly urge Iran to cooperate with the IAEA and comply with relevant security council resolutions without further delay."