Iran's negotiations with world powers over Tehran's nuclear program reached "a turning point" this week, Iranian Foreign Minister Ali Akbar Salehi said on Thursday.

Speaking to the Austrian network ORF during a visit to Vienna, Salehi said, “I call it a milestone. It is a turning point in the negotiations.”

He added, “We are heading for goals that will be satisfactory for both sides. I am very optimistic and hopeful.”

Meeting in Kazakhstan, Iran and world powers agreed on Wednesday to hold new talks in March and April over the Islamic Republic's disputed nuclear drive.

There was no sign of a major breakthrough over Iran's nuclear ambitions in the Kazakh city of Almaty but the agreement on new meetings suggested potential for progress.

Reports published before the talks said the P5+1 group could consider easing sanctions on Iran's gold and precious metals trade, if Iran agrees to close down its underground uranium enrichment plant in Fordow.

However, the New York Times reported on Wednesday that the six powers had watered down their offer to Iran, dropping their demand that the Islamic Republic shut down its enrichment plant at Fordow and insisting instead that Iran suspend enrichment work there and agree to take a series of steps that would make it hard to resume producing nuclear fuel quickly.

The six also agreed, in another apparent softening, that Iran could keep a small amount of 20 percent enriched uranium — which can be converted to bomb grade with modest additional processing — for use in a reactor to produce medical isotopes.

Senior Western diplomats told the New York Times that Iran had not responded to the proposal of the six and that real bargaining had not yet begun. A senior American official described the meeting as “useful” — refusing to call it positive — and emphasized that it was “concrete results” that counted, not atmospherics.

A senior European diplomat was even more skeptical, telling the newspaper that the technical meeting was essentially to explain the proposal to the Iranians once again, and that Iran might very well come back in April with an unacceptable counterproposal that swallows the “carrots” of the six and demands more.

Iran admitted in the past it was moving more centrifuge machines for enriching uranium to the underground Fordow facility, which is carved into a mountain to protect it against possible attacks.

The existence of the facility near Qom only came to light after it was identified by Western intelligence agencies in September 2009. The UN’s nuclear watchdog has already confirmed that Iran begun enriching uranium at the plant.

In a separate interview with the Austria Press Agency on Thursday, Salehi was asked about Iran's enriching uranium to 20 percent purity, responding that nearly 100 kg of the roughly 250 kg of uranium Iran has enriched to 20 percent purity so far had been processed into fuel plates for the research reactor.

"So far we have produced two of these plates per month. In the future we want to produce three, four or perhaps even more fuel plates every month. This is how we want to reduce the supply of 20 percent enriched uranium in the medium term," he said.