British Prime Minister Gordon Brown says the burden must be put on Iran, rather than the West, to prove that its nuclear program is not directed at military purposes.

Britain's Brown whose country possesses nuclear weapons told journalists present at the G8 summit in Italy that a tougher nuclear regime was needed, under which the countries that do not possess nuclear weapons, such as Iran, ought to shoulder the responsibility to prove the peaceful nature of their nuclear work.

"We need a tougher regime so the onus will be on the countries that do not have nuclear weapons to prove this... If there is an international agreement that requires all countries to be open with the rest of the world then Iran would have to prove to us that it did not have nuclear weapons, rather than us to prove they were developing nuclear weapons."

The premier who insisted that London would not unilaterally reduce its nuclear weapon cache warned against a prospect of a world with more nuclear weapons states.

"When the Non-Proliferation Treaty was signed there were five nuclear weapons states. Now there are nine and the possibility of Iran, North Korea and others may seek to acquire nuclear weapons and we will have a big rise in nuclear weapons states in this decade. That is a problem for the whole of the world that has got to be addressed."

Brown however added that he did not want to treat countries like Iran as "guilty until proven innocent," but insisted that nations signing non-proliferation agreements should prove that they are complying with them.

"It is not guilty unless proven innocent, but if a country has accepted an obligation not to have nuclear weapons then you have got to prove and demonstrate that is the case, and I would think people would think that is fair."

The West, spearheaded by the US and Israel, the sole possessor of a nuclear arsenal in the Middle East, accuse Iran -- a signatory to the nuclear Non-Proliferation Treaty (NPT) -- of pursuing a nuclear weapons program.

This is while Tehran has repeatedly said that a military nuclear program does not fit within its defense paradigm, saying that its nuclear program is aimed at producing electricity to meet growing domestic demand.

Brown makes the remarks as the International Atomic Energy Agency (IAEA) which has conducted the largest amount of inspections in the history of the organization on Iran's nuclear activities has not found any evidence proving Tehran has been pursuing a nuclear weapons program.

Britain is among the countries with the largest caches of nuclear munitions in the world. It was also the third state to test an independently developed nuclear weapon.

AR/JG/DT