KYIV (Reuters) - Ukraine's court froze property owned by former President Petro Poroshenko as part of a formal investigation into alleged high treason by the former head of state, the Prosecutor General's office said on Thursday.

       Ukrainian prosecutors have said Poroshenko was involved in financing Russian-backed separatists in eastern Ukraine in 2014-2015. He denies the allegations.

       "The court decided to seize the suspect's property, which belongs to him on the right of ownership," the Prosecutor General's office said in a statement.

       Last month, prosecutors asked a Ukrainian court to arrest Poroshenko with the possibility of bail set at 1 billion hryvnia ($37 million).

       Poroshenko, one of Ukraine's richest citizens, has been outside Ukraine since late December and has not yet commented on the ruling. He has said that he plans to come back to Ukraine on Jan. 17.

       Poroshenko's allies said the seizure of assets was a result of President Volodymyr Zelenskiy's personal revenge.

       "A weak president ... uses manual prosecution, manual investigation, and manual justice to punish opponents," Volodymyr Ariev, a lawmaker from Poroshenko's political party said after the court's decision.

       "This unlawful decision aggravates the political crisis in the country," Iryna Gerashchenko, another lawmaker from his party said on Facebook.

       (Reporting by Natalia Zinets and Pavel Polityuk; Editing by Jon Boyle and Emelia Sithole-Matarise)