TEHRAN: Iran's supreme leader Ayatollah Ali Khamenei condemned on Wednesday the deadly twin bomb blasts at the Boston Marathon but also chided what he described as a “contradictory” US approach to terrorism.

“The Islamic Republic of Iran, as a follower of the Islamic rationale, is against any blast and killing of innocent people whether in Boston, Pakistan, Afghanistan or Syria,” Khamenei said in remarks on his website, leader.ir.

“The approach of the US and others who advocate human rights is contradictory in regards to the killing of innocent people,” Khamenei said in a speech to army personnel and families.

They “remain silent on killing the innocent people of Pakistan, Afghanistan, Iraq and Syria and then fill the world with a hue and cry following a couple of blasts in the US,” he added.

The two bombs, which struck one of America's top sporting events on Monday, killed three people and wounded more than 170.

On Tuesday, Iran's foreign ministry spokesman “strongly condemned” the blasts, calling them a “source of sorrow.”

The two adversaries, which have had no diplomatic relations for more than three decades, do not see eye to eye on a broad range of issues, including Tehran's disputed nuclear programme and its support for the Syrian regime.