TEHRAN (AP) ― Senior investigators from the U.N. nuclear watchdog ended two days of intensive talks with Iranian officials on Thursday over allegations the Islamic Republic may have carried out tests on triggers for atomic weapons.

The semiofficial Fars news agency said the two sides agreed to hold another round of negotiations on Feb. 12.

Fars and other Iranian media did not say if any progress was made, but a senior diplomat from an International Atomic Energy Agency member state in Vienna said shortly before talks ended that they were “not goinag well.” He demanded anonymity because he was not authorized to divulge confidential information.

U.N. team leader Herman Nackaerts had hoped the IAEA would be able to “finalize the structured approach” that would outline what the agency can and cannot do in its investigation.

The IAEA wants to revisit Parchin, a military site southeast of Tehran, to probe allegations that Iran may have tested components needed to develop a nuclear weapon. Tehran has steadfastly denied any such activity.

Iran says the agency’s suspicions are based on forged intelligence provided by the CIA, the Israeli Mossad, Britain’s MI-6 and other intelligence agencies, materials it has not been allowed to see.

Iranians say they have bitter memories of allowing IAEA inspections and replying to a long list of queries over its nuclear program over the past decade. Tehran has in the past allowed IAEA inspectors twice into Parchin, but now it says any new agency investigation must be governed by an agreement that lays out the scope of such a probe.

Iran says it cannot allow its security to be compromised by allowing the IAEA access to non-nuclear facilities simply on the basis of suspicions raised by foreign intelligence agencies Tehran considers enemies.