Iran on Wednesday said Bahrain had made a "strategic mistake" in asking Gulf troops to help quell pro-democracy protests, as President Mahmoud Ahmadinejad blamed the United States for the move.
Defence Minister Ahmad Vahidi told the official IRNA news agency the Sunni Muslim-ruled but Shiite-majority Gulf kingdom had committed a "strategic and political" blunder that would cost its "legitimacy."
Armed forces from Saudi Arabia and the United Arab Emirates rolled into Bahrain on Monday at the invitation of the monarchy to help confront Shiite-led anti-regime protesters.
"Such actions will increase tensions and undermine regional stability and security. And if such inconsiderate and illegal actions become routine, the region will become a hotbed of hostility and conflict," Davari said.
King Hamad on Tuesday declared a three-month state of emergency, giving the military broad powers to curb unrest and restore order.
The authorities on Wednesday imposed a curfew in Manama's Pearl Square and its financial district, after security forces cracked down on a peaceful pro-democracy protest camp.
Three protesters and two policemen were killed on Wednesday, and a third policeman died of wounds sustained earlier, opposition and official sources said.
Mainly Shiite Iran was quick to accuse its arch-foe the United States of supporting military intervention and the violent crackdown in Bahrain, home of the US Fifth Fleet.
"The expedition is a very foul and doomed experience and regional nations will hold the American government responsible for this," Ahmadinejad told reporters after a cabinet meeting on Wednesday.
"The US seeks to save the Zionist regime and to smother the popular movements" in the region.
"And that is why it supports certain (regional) governments," said Ahmadinejad, under whose presidency animosity between Tehran and Washington has reached new heights.
"Unfortunately there is a mobilisation against the population in Bahrain today, which is a very foul, unjustifiable and incomprehensible act. How can those who use weapons against their people want to govern them?" he asked.
Ahmadinejad called on Bahraini officials to yield to the "legitimate" demands of the majority Shiite opposition.
"In a population of 700,000 people, 600,000 are protesting and demand change. The people should be respected and reforms should be carried out... Think about your future," he said.
The main Shiite opposition alliance says it wants a constitutional monarchy, but more radical Shiite groups have said they want rid of the Sunni dynasty that has ruled Bahrain for more than 200 years.
King Hamad has offered dialogue and a new, empowered parliament and other reforms, but the opposition has refused to sit down to talks until the government resigns.
Ahmadinejad also issued a veiled warning to Riyadh and Abu Dhabi to remember Iraq's former dictator Saddam Hussein, who attacked both Iran and Kuwait before falling in the 2003 US invasion of his country, state broadcasting reported.
"The US is not a trustworthy and faithful friend to you, and so far it has sacrificed all of its friends, including Saddam," he said, without directly naming Saudi Arabia or the United Arab Emirates.
Iran's Revolutionary Guards, meanwhile, said Washington would pay a heavy price for supporting the repression of Muslims in Bahrain, the Middle East and North Africa, IRNA reported.
"Dispatching troops by Saudi Arabia and the UAE into Bahrain has been carried out with the support and coordination of the United States," said General Yadollah Javani, a Guards deputy commander in charge of political affairs.
"The escalation of protests in Bahrain endangers the interests of Washington," he said, adding that the United States will lose an "important base" in the region if the Bahraini dynasty is overthrown.