The extended negotiations on Iran's nuclear program continued Thursday in Lausanne, Switzerland, with U.S. Secretary of State John Kerry meeting with Iranian Foreign Minister Javad Zarif.

State Department spokeswoman Marie Harf said on Twitter that the officials talked for several hours early Thursday along with experts from the Iranian and international delegations before taking a break.

Earlier she cited continued progress, but said negotiators "have not reached a political understanding."

Iran and the group that includes the U.S., Britain, China, France, Russia and Germany met all day Wednesday trying to close the remaining gaps in a framework deal to curb Iran's nuclear program in exchange for sanctions relief.� They had set a Tuesday deadline for agreeing to an outline, but with no deal in place decided to keep the negotiations going.

Iran's chief nuclear negotiator, Abbas Araqchi, told Iranian state television on Wednesday that his delegation insists on having an outline in place for lifting all international sanctions against his country before it agrees to a deal.� Other sticking points included details about Iran's future research and nuclear development.

If the two sides can reach a framework deal, more work would remain to come up with a detailed final agreement by a June 30 deadline.

Iran denies wanting to build nuclear weapons and insists its program is solely for civilian purposes.

By VOA