The group says in a report released today that such a strike could have "highly dangerous" consequences, including further destabilizing neighboring Iraq, undermining efforts for Israeli-Palestinian peace, strengthening Iranian hard-liners, and driving up world fuel prices.
"We think that it is important that every effort is made to pursue a
diplomatic option because we think that the consequences of military
action are just far too serious and would be unthinkable in their
extent and damage,"Adam Leach, the director for the Middle East at the charity group Oxfam, told RFE/RL.
The report urges Blair to pressure the United States to engage in talks with Tehran.
Groups backing the report include British trade unions, Oxfam, the Muslim Council of Britain, Christian Solidarity Worldwide, and the left-leaning Foreign Policy Center think tank.
The United States, which has accused Iran of secretly trying to make nuclear weapons, has declined to rule out possible military action if Iran does not halt its nuclear activities. The United States also accuses Iran of supporting insurgents in Iraq.
Iran denies any effort to develop nuclear bombs.
(with material from AP, AFP, BBC)