Head of Zakarpattia Regional State Administration Hennadiy Moskal has written a letter of resignation without specifying the reasons behind his decision, a source in the Ukrainian authorities has told Interfax-Ukraine.

"Indeed, he [Moskal] wrote a letter of resignation, but didn't explain his reasons to anybody, [then he] switched off his phone," the source said.

Neither Moskal nor members of his staff have responded to Interfax-Ukraine's requests for further information.