Farzad Farhangian, 47, called for the overthrow of Iranian President Mahmoud Ahmadinejad at a news conference, where he was accompanied by a former Iranian consul in Norway who defected in January.

"Given the recent event in Iran, yes, I want this government overthrown," said Farhangian, who said he was a deputy consul in Brussels with responsibility for media affairs.

He added that he was putting his weight behind a group called "Green Embassy" composed of a handful of exiled Iranian diplomats, including Mohammad Reza Heydari, the former consular official in Norway who now lives in Oslo.

Farhangian said he left his job in Brussels last week after a year of conflict with the ambassador there over alleged fraud in Iran's 2009 presidential election and subsequent crackdown on protesters inside Iran.

When he left, he said, a "delegation" of officials from Iran was on its way to Brussels to deal with his case. He said his family members would also be seeking asylum in Norway.

He said he had no prior connection to Norway but came to be with Heydari. He said he was also "old friends" with Hossein Alizadeh, who resigned last week from the Iranian embassy in Finland to join the political opposition.

Farhangian said Iran's Ministry of Foreign Affairs has reacted to the series of diplomatic defections with pressure on remaining staff.

"There have been meetings and there have been directives and warnings, because the Iranian government is aware of the danger," he said.

Ahmadinejad has angered hard-liners recently by appointing four close allies to new foreign policy posts, sidelining the Foreign Ministry and snubbing calls to sack his controversial chief of staff whom he made Middle East envoy.

"This is evidence of a continued, deeper issue and divide in the Iranian establishment," Mark Fitzpatrick, senior fellow at the International Institute for Strategic Studies, said of the defections.