Washington has warned that it will not tolerate Iran supporting armed groups fighting in Iraq, but in the far northeast of the country Al Jazeera discovered armed Iranian exiles training to overthrow the government in Tehran.

From their base the fighters cross the porous border into Iran to carry out attacks. Al Jazeera witnessed a group of highly motivated men carry out a mock attack on Iranian forces.

Komala, otherwise known as the Revolutionary Toilers of Iran, was founded in 1969, and is affiliated to the Communist party of Iran but has softened its left-wing stance in recent years.

The United States has become interested in working with the group and last year Abdullah Muhtadi, a senior representative of the party, travelled to Washington for a conference of Iranian minority groups.

Read More</a>