The authorities in Belarus have been urged to release all political prisoners, during the monthly human rights debate on 10 March 2011.
MEPs focused on the cases of opposition presidential candidate Ales Michalevic and journalist Natalia Radin, who have both been subject to prison sentences for allegedly inciting riots.
Mr Michalevic has claimed that he and other political prisoners have been subject to torture.
Opening the debate, Spanish green MEP Raul Romeva I Rueda condemned all uses of torture in the country.
EU High Representative Baroness Ashton has warned Belarus that the EU "will and must act" over Belarus's disputed presidential elections.
Elections in December saw the country's incumbent president Alexander Lukashenko re-elected for a fourth term, in a poll that international observers described as "deeply flawed".
Security forces in the capital Minsk arrested and imprisoned more than 600 opposition activists in riots that took place after the election which saw President Lukashenko returned to power with a reported 80% of the vote.
At least seven presidential candidates were among those detained and some of them were reportedly also beaten by police.
British Conservative foreign affairs spokesman Charles Tannock said "Belarus is European, and so we must act".
Read Democracy Live's guide to how the plenary sessions work