THE HAGUE, Netherlands -- Dutch prosecutors investigating the downing five years ago of Malaysia Airlines Flight 17 over eastern Ukraine want to speak to a man being held by Ukrainian authorities, calling him a “person of interest” in their probe, a spokeswoman said Tuesday.

The fate of Volodymyr Tsemakh could be a factor in the stalled prisoner swap between Russia and Ukraine as Dutch prosecutors want him to remain in Ukraine.

Unconfirmed reports have suggested that Tsemakh is on the list of prisoners that Moscow wants exchanged in return for freeing prisoners including 24 sailors captured off Crimea in November.

Brechtje van de Moosdijk, a spokeswoman for the Joint Investigation Team looking at the downing by a surface-to-air Buk missile of the Malaysian flight on July 17, 2014, told The Associated Press in a telephone interview that Tsemakh is currently in a Ukrainian jail, “but if he's being swapped then, well, of course it's hard to say that we can speak to him when he would be in Russia.”

The international investigation team is seeking to prosecute those responsible for the downing of the flight known as MH17 and the murder of all 298 people on board when the Boeing 777 heading from Amsterdam to Kuala Lumpur was blown out of the sky over conflict-hit eastern Ukraine.

The team has indicted four people so far, three Russians and a Ukrainian, but Tsemakh is not among the four.

“The Dutch public prosecutor would like to have Mr. Tsemakh in Ukraine so he's available for the investigation and we can ask him further questions,” Van de Moosdijk said.

Ukrainian officials would not comment on reports that Tsemakh is on the prisoner swap list but Daria Moroz, an official in the rebel-held Donetsk, told Russian media on Monday that Tsemakh is part of the swap.

Tsemakh, who was the commander of the separatists' air defence in the area where the plane was shot down, was abducted by the Ukrainian Security Service (SBU) earlier this summer from his home in the rebel-held eastern Ukraine as a potential key witness in the MH17 probe.

Tsemakh has not made any public appearances in Ukraine, and he is believed to be in Ukrainian custody after a Kyiv court in July ordered to keep him behind bars.

The trial for the four suspects is set to begin next March in the Netherlands, though it appears unlikely any of them would be brought before the court, since Russia and Ukraine forbid the extradition of their citizens.

Russia's Foreign Ministry called the charges against the country's citizens “absolutely unfounded” and accused the investigators of using “dubious sources of information” and ignoring evidence provided by Moscow in order to discredit Russia.

Nataliya Vasilyeva in Moscow and Yuras Karmanau in Minsk, Belarus, contributed to this report.