Simon Ostrovsky, an American correspondent for Vice News, was reportedly taken hostage on Tuesday in the eastern Ukrainian city of Sloviansk.

Vyacheslav Ponomarev, Sloviansk's "people's mayor," confirmed the news at a press conference, though he later claimed Ostrovsky is in Sloviansk working on a story.

"Nobody abducted him, nobody is holding him hostage, he's with us now in at the SBU, preparing material and working," Ponomarev said, according to The Interpreter.

On Monday, just prior to his disappearance, Ostrovsky tweeted that Ponomarev had threatened reporters at a press conference.

Irma Krat, journalist/Maidan activist, held by pro-Russians and wheeled out for world's weirdest press conference pic.twitter.com/jraT0za39t — Simon Ostrovsky (@SimonOstrovsky) April 21, 2014

Sloviansk pro-Russia 'mayor' threatens to throw journalist out for "provocative" question about former mayor being held under guard — Simon Ostrovsky (@SimonOstrovsky) April 21, 2014

Now he's not letting reporters leave the press conference: "you'll go as you came in. In a group." That's one way to guarantee coverage. — Simon Ostrovsky (@SimonOstrovsky) April 21, 2014

VICE News issued a statement Tuesday afternoon:

VICE News is aware of the situation and is in contact with the US State Department and other appropriate government authorities to secure the safety and security of our friend and colleague, Simon Ostrovsky.

Graham Phillips, a British journalist in Sloviansk, reported on Twitter that Ostrovsky may be released soon.

Back from City Hall for few mins. Atmos there very calm. For those worrying, I honestly feel that Simon /Freddie detained, but likely ok. — GrahamWPhillips (@GrahamWP_UK) April 22, 2014

Ostrovsky's latest dispatch, from Kramatorsk, Ukraine, was posted on Sunday: