A Ukrainian minister has claimed a passenger jet meant to evacuate people fleeing Afghanistan to Ukraine was hijacked at gunpoint and flown instead to Iran, in an unconfirmed incident that was later denied by his own government.

Ukraine’s deputy minister for foreign affairs, Yevhen Yenin, said armed hijackers seized the plane at Kabul’s Hamid Karzai international airport, where a multinational evacuation is under way ahead of a 31 August deadline for foreign militaries to leave the country set by the Taliban.

“Our plane was hijacked last Sunday by [unknown] people,” Yenin told Ukrainian public radio. “They were armed, including with firearms. On Tuesday, our plane was effectively stolen – it flew to Iran with an unknown group of passengers onboard instead of carrying out the Ukrainians.”

It was not immediately clear whether Yenin meant the incident occurred on 15 August, as the Taliban entered Kabul, or on 22 August, and why there was a two-day gap between the hijacking and flight.

A Ukrainian foreign ministry spokesperson later denied the claim, telling the local internet television station, Hromadske, that Yenin was trying to describe the difficulties faced by Ukrainian pilots during the evacuation of Kabul.

Ukraine has evacuated 256 citizens on three flights, the spokesperson said, adding that all aircraft being used to evacuate Ukrainian citizens from Afghanistan were currently in Ukraine.

An Iranian official also denied the hijacking claims, saying that the plane had landed in Mashhad, a city in the country’s north-east, for refuelling before continuing on to Kyiv.

FlightRadar data shows that a Ukrainian plane previously leased to the private Afghan airline Kam Air flew from Kabul to Mashhad on Monday, not Tuesday as Yenin said. Later on Monday, the plane flew from Mashhad to Kyiv, Flightradar data showed.