A prominent security think tank says there is now a low probability of a US military attack on Iran over the country's nuclear program.

The London-based International Institute for Strategic Studies (IISS) announced on Tuesday that there is no short-term prospect of a US strike on Iran, despite the fact that Tehran remains intent on continuing its nuclear activities.

IISS director-general and chief executive Doctor John Chipman said that the US National Intelligence Estimate, which concluded Tehran is not running a nuclear weapons program, 'changed the dynamics of efforts to curb Iran's dual-use nuclear program'.

"Tehran is moving ahead with a new generation of more efficient centrifuges," Chipman continued.

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This is while the UN nuclear watchdog says Iran's nuclear program is in line with power generation for its nation.

He added that Russia's delivery of 82 tons of uranium fuel, which will be used in Iran's nuclear power plant in Bushehr, 'removed another form of leverage over Iran'.

Iran says as a signatory to the Non-Proliferation Treaty (NPT), it is entitled to use nuclear technology for peaceful purposes and therefore refuses to halt its uranium enrichment program.