The EU's diplomatic chief Javier Solana said Saturday there had been "insufficient" progress in attempts to persuade Iran to give up its nuclear programme following high-level talks in Geneva.
The international community was still waiting for a response from Iran on a proposed package of incentives if Tehran gave up its nuclear programme after talks in Geneva, he said.
"It was a constructive meeting, but still we didn't get the answer to our questions," said Solana.
"We hope very much we get the answer and we hope it will be done in a couple of weeks."
Iran's top nuclear negotiator Saeed Jalili described the talks as "constructive and progressing" in comments to reporters afterwards.
He added that "on the manner of continuing the negotiations we have understood better our mutual positions."