A significant proportion of the weapons used by insurgents in Iraq comes either from or through Iran, Britain said Monday. British troops supporting Iraqi border forces have seized large amounts of weapons traced back to Iran, Defense Secretary Des Browne told lawmakers. "There is evidence to suggest a significant proportion of the equipment and the armaments being used by insurgents used in Iraq is of Iranian origin or has been transited through Iran," he said. Browne said Iran's support of insurgent groups in Iraq is unacceptable. He said Britain was trying to convince the Islamic republic that it was in its long-term interest to avoid instability in the region. Browne's statements provided qualified backing to US accusations that Teheran is funneling weapons to Iraqi militias. Last week top US defense officials accused Iran of increasing its support for the militias, warning that all military options to deal with the situation were on the table.