WARSAW, Sept. 30 - European Union leaders expressed concern Friday with the criminal trials of opposition politicians in Belarus and Ukraine, and warned that international grants and loans were at stake if Belarus didn’t release political prisoners immediately.

They also said they put pressure on Ukraine to end the trial of the country’s former prime minister, Yulia Tymoshenko, The Wall Street Journal reported.

Belarus should immediately release political prisoners arrested after last year’s presidential election and begin talks with the country’s opposition, said European Council President Herman Van Rompuy, European Commission President Jose Barroso, and Polish Prime Minister Donald Tusk at a summit of the bloc’s Eastern Partnership program for European former-Soviet states. Poland holds the EU’s rotating presidency until the end of the year.

“We assume that grants and loans from international institutions would be possible, like the International Monetary Fund and the European Investment Bank, up to $9 billion, as well as investment incentives and mechanisms for stabilizing the Belarusian currency, at $1 billion each, and also a more relaxed visa regime,” Tusk told a press conference after the summit. “The conditions for starting these should be full amnesty and rehabilitation of prisoners arrested after elections, talks between the government and the opposition, and parliamentary elections that would comply with OSCE standards.”

Van Rompuy said the EU won’t be fully engaged in cooperation with Belarus if the prisoners aren’t released and rehabilitated.

Belarussian Foreign Minister Sergei Martynov turned down an invitation to attend the summit, and the country’s ambassador also didn’t attend, despite an invitation. The seats of the Belarus delegation at the talks stood empty, a day after EU leaders said they would no longer deal with authoritarian leader Alexander Lukashenko until the regime respected human rights.

The EU leaders also said they put pressure on Ukraine to end the trial of the country’s former prime minister, Yulia Tymoshenko, accused of exceeding her authority in sealing a gas-supply deal with Russia in 2009. Mrs. Tymoshenko said earlier the trial was a case of “political lynching.”

Van Rompuy said the Tymoshenko case was being raised with the Ukrainian delegation, headed by President Viktor Yanukovych, who defeated the former prime minister in presidential elections in 2010.

“We expressed concern over her fate,” Van Rompuy said.

Ukraine is likely to conclude its EU association talks later this year, but Tymoshenko’s case may weigh on the negotiations, Tusk said. (wsj/ez)