An Austrian court on Tuesday approved a US request to extradite a Ukrainian billionaire with ties to an associate of Donald Trump to face trial on bribery charges, in a move that could test the White House's relationship with Russia.

Immediately after the decision Dmytro Firtash was detained on a European arrest warrant related to a separate request by Spain, however, throwing the likelihood of extradition into doubt.

The court in Vienna said Mr Firtash, a former ally of deposed Ukrainian president Viktor Yanukovych who is also seen as close to the Kremlin, must be sent to face the charges in Chicago, overturning a previous ruling that had rejected the extradition request as politically motivated.

"The (appeal against the previous decision) has been granted," the Judge Leo Levnaic-Iwanski told the court.

"This does not mean that somebody is being pre-judged as guilty, but rather that it will be decided in another country whether they are guilty or innocent,” he added.