A senior Ukrainian prosecutor says that authorities are investigating whether the imprisoned ex-Prime Minister Yulia Tymoshenko was involved in a contract-style killing 15 years ago.

A televised statement made late Friday by Deputy Prosecutor General Renat Kuzmin further dims hopes that Tymoshenko, sentenced to seven years in jail earlier this month, could be released any time soon.

Kuzmin said that prosecutors are looking into claims that Tymoshenko was involved in the slaying of a lawmaker and businessman in 1996.

The West has criticized Tymoshenko's jailing on charges of abuse of office as the politically motivated prosecution of a top opposition leader by her longtime foe, President Viktor Yanukovych.

Tymoshenko's office denied the new allegations.