BRUSSELS, May 15 - Ukraine's prime minister said Tuesday that his predecessor had been correctly convicted of abusing her powers in signing a gas deal with Russia, and invited European observers to watch her appeal.

On a visit to Brussels, Prime Minister Mykola Azarov said his predecessor, Yulia Tymoshenko, had been convicted and sentenced to seven years in prison by a judiciary that was free and independent. Tymoshenko's appeal, however, was postponed in Ukraine on Tuesday on what her lawyers called political grounds.

Azarov invited observers from the European Union nations to Ukraine to watch the appeal process.

"They can review the documents. They can learn more about the procedure and they can listen to the arguments," The Associated Press quoted Azarov as saying.

Azarov said it was already clear she falsified documents that led Ukraine to pay $8 billion a year extra for a gas contract with Russia. Last year, the prosecutor’s office said Tymoshenko's actions cost the state $440 million in damages.

The 27-nation European Union has criticized her sentence as being politically motivated.

Tymoshenko has accused President Viktor Yanukovych, the longtime rival who narrowly defeated her in the 2010 presidential election, of jailing her to prevent her from posing a challenge in October parliamentary elections.

Prosecutors argued Tuesday that the appeal should be postponed because Tymoshenko is undergoing medical treatment for a back condition in a hospital in Kharkiv, the city where she is imprisoned, and would be unable to appear in court in Kiev, the capital.

In ruling in favor of the prosecution, the High Specialized Court for Civil and Criminal Cases set a new date of June 26, which falls near the end of the European soccer championship.

Some EU officials and governments have vowed to boycott the games in Ukraine over Tymoshenko's imprisonment.

Tymoshenko's lawyer, Serhiy Vlasenko, condemned the postponement.

"Today's decision is complete nonsense on the level of the country's highest court," he told reporters. "Today, Yanukovych has again spat in the face of Europe."

He said the delay was aimed at preventing Tymoshenko from appealing to the European Court of Human Rights, which can be done only after the appeals process has been exhausted at home, but Vlasenko said they would go ahead and do so anyway.

Azarov insisted Ukraine's judicial institutions were impartial and invited EU observers to come check it during Tymoshenko's appeal.

“We are ready to invite to this process the representatives of the judicial services of the European countries. They can review the documents. They can learn more about the procedure and they can listen to the arguments," he said. (ap/ez)