TEHRAN — A senior Iranian official in talks on the country's disputed nuclear program has said differences remain on key questions at the ongoing negotiations in Geneva, state media reported on Monday. “The gap still exists, differences exist, and all parties are negotiating with seriousness and determination, but we haven't found solutions to key questions,” Deputy Foreign Minister Abbas Araghchi said. He was speaking after three hours of talks on Sunday night between US Secretary of State John Kerry and Energy Secretary Ernest Moniz and their Iranian counterparts Mohammad Javad Zarif and Ali Akbar Salehi. The US and Iranian officials began their talks on Friday. Parallel negotiations were held on Sunday between Tehran and senior negotiators from the so-called P5+1 group — UN Security Council permanent members Britain, China, France, Russia and the United States plus Germany. “In many areas, the negotiations have addressed the details... In some cases, solutions were found and the time has come for political decisions,” said Araghchi, quoted by state television. “For this reason, contacts at the highest level between the two parties are needed,” he added. Iran and world powers are trying to strike a deal that would prevent Tehran from potentially developing a nuclear bomb in return for an easing of punishing international economic sanctions. Kerry and Zarif are holding a second day of discussions on Monday as the clock ticks down to a March 31 target for a framework accord. Washington and Tehran's top diplomats sat down on Monday for a second day of talks on Iran's nuclear program as they struggled to narrow gaps ahead of a key deadline. Before the talks, Kerry also acknowledged that there were “still significant gaps. There is still a distance to travel.” In a sign of the growing push for an accord, US Energy Secretary Ernest Moniz is taking part in the talks for the first time, as is Ali Akbar Salehi, the director of the Iranian Atomic Energy Organization. Both men led five hours of negotiations on Saturday, before Kerry's arrival, and took part in the discussions between the two top diplomats Sunday night and Monday morning. Observers have suggested their participation could be a sign a deal is within reach. But Kerry played down the importance of adding new negotiators to the mix, saying Moniz was present because of the “technical” nature of the discussions. While the political aspects of the deal must be nailed down by the end of next month, the deadline for signing the full agreement is June 30 — a cut-off point that looms all the larger after two previous deadlines were missed. With both Washington and Tehran under pressure from hardliners at home eager to torpedo the deal, observers agree a new extension is unlikely. — Agencies