Vienna, Austria ? Senior negotiators for Iran and the European Union reported progress Saturday at talks meant to find common ground for resolving Tehran’s defiance of a U.N. demand that the Islamic republic freeze uranium enrichment or risk sanctions.

In an encouraging sign, the two sides agreed to have further discussions today.

“We had some good and constructive talks and we have made some progress in some areas, and we shall continue … tomorrow,” chief Iranian nuclear negotiator Ali Larijani said, speaking through an interpreter.

Cristina Gallach, spokeswoman for Javier Solana, the EU’s foreign policy chief, confirmed that talks would continue today. “The feedback from the table is that the talks have been constructive and positive,” she said.

The discussions have been billed as possibly the last chance for Iran to avoid sanctions for rejecting the U.N. Security Council’s demand that it suspend its uranium enrichment processes, which can be misused to make nuclear bombs.

Being held at the Austrian chancellor’s office, the talks are looking for a basis to open negotiations between Iran and six world powers that have offered a package of economic and diplomatic incentives meant to persuade Tehran to limit its nuclear program.

The five permanent Security Council members – the U.S., China, Britain, France and Russia – along with Germany have demanded that Iran halt enrichment as a condition for the talks, but the Iranians have refused to do so.

With the two sides seemingly so far apart, hopes for success had been slim for the mission by Solana, who is formally authorized by the six powers to carry their message and listen to the Iranians, without actually negotiating. Still, positions appeared to have shifted slightly.

European officials, who insisted on anonymity for sharing confidential information, suggested that some of the six nations were at least ready to listen if Iran committed itself to an enrichment freeze soon after the start of negotiations instead of doing so as a condition for such talks.

The officials declined to provide details. But such a readiness would deal a blow to U.S.-led attempts to hold fast to the demand that Iran freeze enrichment before any talks commence – or face the prospect of Security Council sanctions.