Canada has closed its embassy in Iran and will expel all remaining Iranian diplomats in Canada within five days, Foreign Minister John Baird said on Friday, denouncing Tehran as the biggest threat to global security.

Baird cited Iran's nuclear program, its hostility toward Israel and Iranian military assistance to the government of President Bashar Assad in Syria, which is locked in civil war with rebels, as the reasons for suspending diplomatic relations.

"The Iranian regime is providing increasing military assistance to the Assad regime; it refuses to comply with UN resolutions pertaining to its nuclear program; it routinely threatens the existence of Israel and engages in racist anti-Semitic rhetoric and incitement to genocide," Baird said in a statement.

"It is among the world's worst violators of human rights; and it shelters and materially supports terrorist groups, requiring the Government of Canada to formally list Iran as a state sponsor of terrorism under the Justice for Victims of Terrorism Act."

Accusing Iran of showing blatant disregard for the safety of foreign diplomats, Baird said "Canada views the government of Iran as the most significant threat to global peace and security in the world today."

"Under the circumstances, Canada can no longer maintain a diplomatic presence in Iran ... Diplomatic relations between Canada and Iran have been suspended," he said.

Prime Minister Benjamin Netanyahu congratulated the Canadian Prime minster Steven Harper on Friday, following Canada's announcement.

"This is a bold decision that is sending a clear message to Iran and to the entire world, one week after a show of anti-Semitism and hate in Tehran. The Canadian government took a moral step," the prime minister said.

"The resolve that was demonstrated by Canada is highly important in order for the Iranian regime to understand that it cannot continue its race toward nuclear weapons. This practical move should set an example for the rest of the international community that needs to join Canada by setting clear red lines for the Iran regime."

Ottawa has long had poor relations with Iran, in part because of its enmity towards Canadian ally Israel.

The United States has not had a functioning embassy in Tehran since the hostage crisis of 1979. Britain downgraded ties with Iran following a major attack on its embassy in Tehran in November 2011, which it insists was sanctioned by the Islamic republic's ruling elite. After the attack, Britain pulled all of its diplomats out of Iran and expelled Iranian diplomats from U.K. soil.

Canada's relations with Iran have been strained since former Canadian ambassador Ken Taylor helped rescue six Americans from Iran during the hostage crisis in 1980.

Relations became even rockier in 2003 after Zahra Kazemi, a freelance photographer with dual Canadian-Iranian citizenship, died in custody after being arrested while taking photographs outside a Tehran prison in 2003. Canada then recalled its ambassador. Iran also ordered Canada's ambassador to leave the country after trying unsuccessfully to come to an agreement on an exchange of ambassadors for some time.

All Iranian diplomats in Canada have now been declared "personae non gratae," Baird said. He also told Canadians to avoid traveling to Iran.