New York, Sep 25 (DPA) Iran's President Mahmoud Ahmadinejad has cancelled a press conference scheduled for later Friday at United Nations headquarters in New York.

No reasons were provided to the UN secretariat, which organises the event for Ahmadinejad each year when he comes to New York to attend the UN General Assembly.

The cancellation coincided with news that Iran has started a second nuclear plant for uranium enrichment. US President Barack Obama said at the G20 summit in Pittsburgh, Pennsylvania that the second plant is 'inconsistent' with claims it is being used to produce civilian nuclear power.

Speaking at the summit and standing alongside British Prime Minister Gordon Brown and French President Nicolas Sarkozy, Obama said the 'disturbing' news of the second facility demonstrates Tehran's willingness to deceive the world and violate international norms.

'The existence of this facility underscores Iran's continued unwillingness to meet its obligations under UN Security Council resolutions,' Obama said.

'It is time for Iran to act immediately to restore the confidence of the international community by fulfilling its international obligations,' he added.