LAUSANNE, Switzerland, March 30 -- All sides in the Iran nuclear talks have made clear what exactly the sticking points are and how these obstacles should be removed in order to achieve a breakthrough, Chinese Foreign Minster Wang Yi said here on Sunday.

"We have achieved some strong common ground during the past efforts and there are only a few problems left blocking our way," Wang said, when commenting on the progress of Sunday and Monday, during which intensive minister meetings were held.

He added he was still optimistic for finding a solution for the remaining balks.

Wang declined to give detailed information for the "remaining balks".

According to the Foreign Minister, there might be some "outcomes" Monday night or Tuesday. He said he hoped "the outcomes will be good ones".

All sides hope to reach visible and tangible outcomes before the end of March, which would pave the path for achieving the comprehensive agreement, Wang said, adding that the format and content of the outcomes is in the process of negotiation.

Wang said China has always actively involved in the negotiations as a constructive player, seeking efforts to bridge gaps and contribute ideas to solve the broad, complex issue.

After many years of nuclear negotiations, progress have been made in many aspects, Wang said, adding he hoped that through the efforts of the foreign ministers from all parties, there will be ultimate solution over the Iranian nuclear issue.

"The final deadline is in the end of June, we still have time," he said.

Negotiations over Iran's nuclear program entered a critical phase on Monday with differences still remaining when the March 31 deadline for a political framework approaches.

On Nov. 24, 2013, the P5+1 and Iran reached a first-step agreement on Iran's nuclear program, the Geneva 2013 Joint Plan of Action, which demanded Iran suspend some sensitive nuclear activities in exchange of limited sanction relief to buy time for the diplomatic effort to resolve the issue.

Since then, the P5+1 and Iran have twice missed self-imposed deadlines for a final and comprehensive accord, respectively in June and November last year, and the negotiators then set March 31 of 2015 as a new deadline for a political framework agreement and June 30 for the final deal, so as to pave the way for the final resolution of the long disputed Iran nuclear issue.