Negotiators said on Wednesday that progress had been made in talks aimed at limiting Iran's nuclear program, but that much work was still needed.

Iran and the P5+1 powers - permanent UN Security Council members Britain, China, France, Russia and the US, plus Germany - missed a midnight Tuesday deadline to reach an agreement.

Negotiations in the Swiss city of Lausanne resumed on Wednesday, a seventh and unscheduled day for talks between foreign ministers, with some stumbling blocks in place.

"There has been progress, but not enough yet for... us to be able to immediately reach a conclusion," said French Foreign Minister Laurent Fabius after leaving the talks to attend a weekly cabinet meeting in Paris.

Fabius said his colleagues remained in talks, and that he would return to Lausanne "as soon as is necessary." He said the Chinese and Russian delegates had already left.

"We made progress, but not on all issues, I left my political director behind, I am in contact with him," said Fabius. The French foreign minister said he would insist on a deal that ensured checks on Iran's compliance.

Berlin remains optimistic

Chancellor Angela Merkel, whose Foreign Minister Frank-Walter Steinmeier was at the talks and who informed her by telephone, said she hoped a compromise would be reached later on Wednesday.

"I hope and I wish that a compromise will be reached today that corresponds to the conditions we have set - namely that Iran gets no access to nuclear weapons," Merkel said.

Meanwhile, Israeli Prime Minister Benjamin Netanyahu - who has repeatedly expressed concern about the terms of any agreement - said on Wednesday that world must insist on a "better deal" linking concessions such as the easing of sanctions with a change in Tehran's behavior.

"Iran must stop its aggression in the region, stop its terrorism throughout the world and stop its threats to annihilate Israel. That should be non-negotiable and that's the deal that the world powers must insist upon," he said.

Netanyahu spoke as the Israeli military confirmed that tests on its new "David's Sling" missile defense shield had been successful. The system is capable of shooting down middle range rockets including Cruise missiles.

rc/jil (AFP, AP, dpa, Reuters)