A Greek prosecutor appealed on Friday against the rejection of a Maltese request to extradite a whistleblower who supplied documents to murdered investigative journalist Daphne Caruana Galizia.
Malta has issued a European arrest warrant for 36-year-old Russian Maria Efimova, who stirred a political scandal over allegations of wrongdoing at Maltese-registered Pilatus Bank.
Ms Efimova, who left Malta last year with her family, turned herself in to Greek police last month. She was arrested under the warrant for alleged misappropriation of funds, accusations that she denies.
A court ruled on Thursday against extraditing Ms Efimova to Malta and ordered her release. Following the prosecutor's appeal, Greece's top court is expected to hear the case, judiciary sources said on Friday.
Ms Efimova was employed for three months in 2016 by Pilatus Bank. Ms Caruana Galizia had identified her as the source of internal bank documents which, she said, indicated that Prime Minister Joseph Muscat's wife Michelle owned a secret company in Panama.
The Muscats have both denied the accusations.
READ: Efimova facing deportation to Malta
A group of 36 European parliament members signed a letter following Ms Efimova's arrest, calling for her not to be extradited to Malta.
Ms Caruana Galizia was killed by a car bomb in October 2017. Three men have been charged with killing her but police have yet to give a motive.
Pilatus Bank has accused Ms Efimova of embezzlement. She denies all charges and has counter-sued the bank for failing to pay her salary.