The US government thought it was very important that the Iranians should "keep their folks at home", he said.

His comments came after US forces detained several Iranians in northern Iraq on suspicion of aiding insurgents, accusations rejected by Tehran.

Mr Cheney is the latest member of the Bush administration to warn that the US will take steps against those trying to destabilise the situation in Iraq.

US officials say five Iranian nationals arrested in Irbil on Thursday are linked to the Iranian Revolutionary Guard, accused of training and arming Shia insurgents in Iraq.

Iran's foreign ministry says the men are diplomats and were working at the Iranian liaison office in Irbil. It has demanded their immediate release.

Washington has often accused Iran, or factions within the Iranian government, of aiding Shia groups in Iraq militarily and politically, but has offered little proof of Tehran's alleged activities.

BBC/VOVNews