Talks with Iran have made progress, but no agreement has been reached on the key issue of uranium enrichment, said European Union (EU) foreign policy chief Javier Solana on Wednesday.

"We have reached common ground on quite a number of subjects. But we haven't agreed on what is a key point: suspension (of uranium enrichment). So far, up to today, Iran has made no commitment to suspend," Solana told the European Parliament's Foreign Affairs Committee.

He said he has been engaged in talks with the Iranian authorities for four months with an aim to clarify whether a negotiation between Iran and six countries -- Britain, France, Germany, the United States, Russia and China -- could start on the basis of a June proposal.

Watch Videos >>>······

The six countries offered Iran a package which included political, economic and nuclear technology incentives in return for Iran's suspension of uranium enrichment.

The six countries have followed a two-track approach: dialogue and referring the case to the UN Security Council, said Solana.

"Dialogue could not last forever. It is up to them (the six countries) to decide whether the time has come to follow the second track," he said. "But the door to negotiations is always open."

He said the issue "can only be solved, and will be solved, through negotiations."

"We have the right framework and the right broad basis for that. Iran will develop a civilian nuclear program, as many other countries in the world. And Iran will do it better and more efficiently if it is done in cooperation with us. From a political and technological point of view both sides have a lot to win. They, and we, know that."

He said solving the problems posed by the Iranian nuclear program will mark a breakthrough in nuclear non-proliferation.

"It will offer a model to be followed by many countries in relation to the development of the fuel cycle," he said.

Solana sees the necessity to cooperate with Iran in a broader sense.