Progress made, but nuclear talks are extended: Kerry

Talks between Iran and six world powers have failed for a second time this year to reach a deal over Tehran's nuclear program.

U.S. Secretary of State John Kerry says negotiators are now aiming to secure an agreement by March, with more time needed to iron out the technical details.

(SOUNDBITE) (English) U.S. SECRETARY OF STATE JOHN KERRY, SAYING:

"We are certainly not going to sit at the negotiating table forever -- absent, measurable progress. But given how far we have come over the past year, and particularly in the last few days, this is certainly not the time to get up and walk away."

Kerry says the talks are tough, and the stakes are high... But he says the world IS safer than it was a year ago.

(SOUNDBITE) (English) U.S. SECRETARY OF STATE JOHN KERRY, SAYING:

"Today IAEA inspectors have daily access to Iran's enrichment facilities and a far deeper understanding of Iran's programme."

But the talks have foundered on the scope of Iran's ura