A preliminary nuclear deal between Iran and six world powers is a firm basis for a future accord that could end a 12-year nuclear standoff between Tehran and the West, though details must be worked out, the top U.S. diplomat said on Thursday.

"The political understanding with details that we have reached is a solid foundation for the good deal we are seeking,” U.S. Secretary of State John Kerry told reporters after the preliminary political deal was announced in the Swiss city of Lausanne.

"We still have many technical details, other issues that need to be worked out," he said, including the possible lifting of a U.N. arms embargo, the modernization of the Arak heavy-water reactor and Fordow underground sites.

He added that the United States remained seriously concerned about Iran’s destabilizing activities in the region.

Russia says deal on Iran nuclear program good for Middle East

The Russian Foreign Ministry said on Thursday a deal in Lausanne over Iran's nuclear program would help the security situation in the Middle East, partly because Tehran would now be able to take more active part in efforts to solve conflicts there.

Iran and major powers reached a framework agreement on Thursday on curbing Iran's nuclear program for at least a decade, after eight days of marathon talks in Switzerland.

U.N. chief: comprehensive Iran deal could enable more cooperation

U.N. Secretary-General Ban Ki-moon said on Thursday a comprehensive nuclear deal between Iran and world powers by June 30 could "enable all countries to cooperate urgently to deal with the many serious security challenges they face."

In a statement, Ban congratulated the sides on their framework agreement curbing Iran's nuclear program for at least a decade that clears the way for talks on a future comprehensive settlement.

Jordan's U.N. ambassador Dina Kawar, who is president of the United Nations Security Council for April, told reporters that she hoped the progress between Iran and world powers could "open up other situations in our region."

When asked for more detail, she said: "Maybe it will give us a chance also to address the issues of Palestine and Israel in the council ... Let's see what happens."

France said last week it plans to start discussions with partners in the "coming weeks" on a United Nations Security Council resolution to lay out parameters for ending the Middle East conflict.