Iran will make the strategic Gulf region unsafe for all if it comes under attack by the United States over its nuclear programme, the deputy head of the elite Revolutionary Guards said on Sunday.

"If the Americans make the slightest mistake, the security of the region will be endangered. Security in the Persian Gulf should be for all or none," Yadollah Javani told the official IRNA news agency.

"The Persian Gulf is a strategic region and if it is endangered they (Americans) will suffer losses and our response will be firm. We will defend ourselves if America or Israel resort to any hostile measures against our vital values," he added.

The international community led by the United States has stepped up pressure on Iran over its controversial nuclear programme amid concerns that the Islamic republic is engaged in a covert nuclear weapons programme, a charge Tehran vehemently denies.

The United States and Israel have not ruled out a military strike to stop Iran's alleged atomic ambitions.

Javani's declaration preceded comments by the top US military officer on Sunday that a plan to attack Iran was ready, if needed to stop the Islamic republic from acquiring a nuclear weapon.

Admiral Mike Mullen, chairman of the Joint Chiefs of Staff, said he was "extremely concerned" about the possible repercussions of such a strike.

Iranian officials have frequently vowed a crushing response to any US and Israeli attacks, AFP reported.