Iran's Foreign Ministry summons the Swiss ambassador, who represents US interest in Tehran, in protest to 'interventionist' statements by American officials on Iran's election.

The ministry also summoned the Canadian charge d'affaires to convey Iran's official protest to Ottawa over the Canadian officials' recent remarks on Iran's presidential vote.

Several European envoys were also summoned on Tuesday over what Iran's Foreign Ministry called 'malicious stance' taken by their countries toward Iran.

On Tuesday, US President Barack Obama expressed 'deep concern' about the post-election unrest in Iran but warned that meddling in Iran's internal affairs would be counterproductive.

"We respect Iranian sovereignty and want to avoid the United States being the issue inside of Iran," he said.

Canadian Foreign Affairs Minister Lawrence Cannon also called on Monday for what he called 'a full and transparent investigation into electoral fraud and discrepancies' in Iran's presidential vote.

Friday's presidential election, which saw incumbent Iranian President Mahmoud re-elected for a second term in office, has caused mass rallies by hundreds of thousands of supporters of former prime minister Mir-Hossein Mousavi who reject the election as fraudulent.

The interior minister, who is appointed by president and is in charge of holding the election, has denied the allegation, saying the ministry adopted methods which could not possibly be subject to 'irregularities'.

At least eight people have been killed so far in recent post-election violence in Tehran.