Experts from the UN's nuclear watchdog agency held talks in Tehran on Wednesday to seek a way forward in resolving perennial concerns over Iran's nuclear program, AFP reported. A team led by the International Atomic Energy Agency's chief inspector Herman Nackaerts and one headed by Tehran's IAEA representative Ali Ashghar Soltanieh kicked off talks to "find a solution to concerns and questions raised by the IAEA," the ISNA news agency reported. ISNA later said that, after "technical discussions," the two sides had agreed to meet again on Thursday. On Tuesday, before flying out from the agency's base in Vienna, Nackaerts had called on Iran to be "constructive." He also repeated "hope" that Iran would grant access to Parchin, a military base near Tehran where the agency's experts suspect Iran could have carried out experiments with explosives capable of triggering a nuclear weapon. "Throughout this process, the director general has always said that we are approaching these talks in a constructive spirit," Nackaerts told reporters. "Also this time we are approaching it in the same spirit, and we trust that Iran will work with us in the same spirit," he added. But the IAEA's hopes of reaching a deal are not high. IAEA head Yukiya Amano said Friday he was "not necessarily optimistic," while a Western diplomat told AFP on Sunday "there still remain some pretty big disagreements" with Tehran. The IAEA, on a visit in mid-December , failed to reach a final agreement for a "structured approach" for Iran to address what it calls "overall, credible" evidence of nuclear weapons research having been carried out until 2003 -- and possibly since then. Iran vehemently denies having ever sought an atomic bomb. On Tuesday, the Iranian foreign ministry spokesman said the government hoped to conclude a comprehensive agreement with the IAEA on Wednesday. But Ramin Mehmanparast said that would only be possible if the agency recognized Iran's "nuclear rights," while playing down the chances that the IAEA team might get access to Parchin. "Parchin has no connection with Iran's nuclear activities," Mehmanparast said. Access to it could be discussed, but only in the context of a possible agreement, he added. Wednesday's talks were monitored by the so-called P5+1 group -- Britain, China, France, Russia, the United States and Germany. Their parallel negotiations with Tehran over the nuclear program are currently stalled. At their last meeting, held in Moscow in June, Tehran rejected P5+1 calls for it to scale back its nuclear enrichment activities, while asking for substantial sanctions relief. On Tuesday, top Iranian lawmaker Aladin Borujerdi repeated Tehran's demands, ISNA reported. "The main focus of the next talks with the P5+1 should be on lifting the sanctions imposed by the U.S. and the European Union," said Borujerdi, who heads parliament's influential foreign policy committee.