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They also claimed to have documents which proved the allegations.

"We possess documents and information showing the direct supports by the US imperialism for this highly disgusting stream in the region which has destroyed the Islamic countries and created a wave of massacres and clashes," Deputy Chief of Staff of the Iranian Armed Forces Major General Mostafa Izadi said.

The alleged American support for ISIS, according to Izadi, is an instrument of "proxy warfare in the region" which is a "new trick by the arrogant powers against the Islamic Republic".

The statement of the Deputy Chief of Staff echoes the remarks made by Iran’s Parliamentary Speaker Ali Larijani on Friday. "The United States has aligned itself with the ISIL in the region," Larijani said,

Iran was rocked by a deadly terror attack on Wednesday which struck in the country’s capital, Tehran.

Seventeen people were killed when four armed assailants attacked the national parliament building, while a suicide bomber blew himself up a museum in the city.

ISIS claimed responsibility for the attack.

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“The terrorist attacks indicated the terrorist groups have failed to achieve their main goal and targeted the parliament and Imam Khomeini Mausoleum, finally resorting to martyring the innocent people and the staff at the parliament,” Larijani added.

On Friday, Iran's supreme leader, Ayatollah Ali Khamenei, said the attacks would only increase Tehran's hatred against the US and its Saudi Arabian "stooges".

In response to the attack, one Republican congressman appeared to praise attack in a speech in Washington DC.

Dana Rohrabacher said; “Isn’t it a good thing for us to have the United States finally backing up Sunnis who will attack Hezbollah and the Shiite threat to us? Isn’t that a good thing?”

Bur speaking in response to Rohrbachers comments Matthew Levitt, director of The Washington Institute’s Stein Program on Counterterrorism and Intelligence, said: "It’s never in our interest to support a terrorist group like the Islamic State.

"We should condemn the attacks in Tehran, as we would condemn any act of terrorism, even as we hold Iran accountable for its sponsorship of terrorism."

The Iranian government is yet to release the documents which it claims prove US co-operation with ISIS.