The Israeli Prime Minister has criticised international officials for a weak response to Iran's nuclear ambitions.

Representatives from the US. Britain, China, Russia, France and Germany met Iranian officials last week for nuclear talks. The discussions were disbanded until May 23, but were labelled "constructive and useful" by Baroness Ashton, the EU foreign policy chief.

Benjamin Netanyahu said they gave the Ahmadinejad regime a "freebie", by allowing Iran to enrich uranium without obstacle for another five weeks.

"It's got five weeks to continue enrichment without any limitation, any inhibition," he said.

President Obama reassured him by saying that if the next round of talks wielded no breakthrough more sanctions would be imposed on Tehran.

"We're going to keep on seeing if we make progress," he said. "The clocking is ticking and I've been very clear to Iran and to our negotiating partners that we're not going to have these talks just drag out in a stalling process.

"So far at least we haven't given away anything."

He said there was still "a window in which to resolve this conflict diplomatically. That window is closing and Iran needs to take advantage of it," he said.

The next meeting will take place in Baghdad.