BEIJING, March 20 -- China on Thursday said it would continue communicating with relevant parties and make contributions to reach an agreement on the Iranian nuclear issue as early as possible.

Talks between Iran and Britain, China, France, Russia and the United States plus Germany, the P5+1, took place in Vienna, Austria, from Tuesday to Thursday. The talks were heading to a comprehensive deal to resolve Tehran's long standing disputed nuclear program.

"We had substantive and useful discussions, covering a set of issues, including enrichment, the Arak reactor, civil nuclear cooperation and sanctions," European Union foreign policy chief Catherine Ashton said in Vienna after the talks.

At a daily press conference, Chinese Foreign Ministry spokesman Hong Lei was asked to comment on the progress.

"The talks were positive," Hong said, noting that relevant parties have expressed political willingness to reach a comprehensive deal as early as possible. They exchanged thorough and frank views and reached some consensus.

According to Hong, although there are still some differences such enrichment and the heavy water reactor, all parties have a willingness to resolve each other's concerns and agreed that the next round of talks would reconvene from April 7 to April 9.

China offered some concrete proposals during the talks and tried to promote parties to expand consensus and narrow differences, Hong said,adding that their response to China's proposals was positive.

China has always had an objective, fair and responsible attitude towards the Iranian nuclear issue and maintains that the issue should be resolved via dialogue, Hong said.

Iran and the six countries struck a six-month interim deal in Geneva, Switzerland, in November whereby Iran would suspend some controversial nuclear activities starting on Jan. 20, while western states would lift some sanctions imposed on Iran.