A leading weapons scientist has warned that a pre-emptive military strike on Iran could accelerate Tehran's drive to acquire nuclear weapons.
Frank Barnaby of the British think-tank Oxford Research Group said Iran could respond to an attack by launching a 'crash programme' to build a crude nuclear device within months.
Mr Barnaby said that there was a 'real possibility' that Iran had constructed further secret facilities in anticipation of military strikes.
The report suggests air strikes, like those reportedly being considered by the US and Israel, would harden Iranian attitudes and political resistance to outside pressure to stop uranium enrichment.
The report has been backed by former International Atomic Energy Agency chief, Hans Blix.
Mr Blix argued that military action would probably result in a high number of civilian casualties, as a surprise attack would inevitably catch many people unprotected.
IAEA meeting in Vienna
The UN nuclear watchdog's governing body is meeting in Vienna today to ratify cuts in technical aid to Iran and scrutinise Tehran's defiant expansion of uranium enrichment, a possible route to atomic bombs.
Six world powers are now negotiating on widening sanctions against Iran for pressing ahead with its programme to enrich uranium and ignoring a 21 February UN deadline to stop.
The reduction in IAEA technical aid to Iran's nuclear energy programme comes almost three months after the UN Security Council banned transfers of atomic technology and expertise to the Islamic Republic.
Iran denies it is secretly trying to develop nuclear weapons, insisting it only wants to generate more electricity.
Iran says UN demands for it to halt uranium enrichment are illegal.
But IAEA efforts to verify that Tehran's work is wholly peaceful have been stalled by Iranian evasions since 2004.
