Belarus has executed two men convicted for a fatal 2011 metro bomb attack, despite protests from European human rights groups and calls for a re-trial.

Belarussian news media reported Saturday that Vladislav Kovalyov and Dmitry Konovalov, both 25, had been executed.

Kovalyov and Konovalov were convicted in November of staging a bomb attack in a central Minsk metro station. The April 11 blast killed 15 people and wounded more than 100 others.

President Alexander Lukashenko had refused to pardon the two, citing the gravity of the crime.

Belarus is the only European country that still uses the death penalty. European leaders and rights groups had urged Minsk not to carry out the death sentences on the two factory workers, and they condemned the executions.

European Union chief diplomat Catherine Ashton said Saturday “the two accused were not accorded due process including the right to defend themselves.”

The executions are likely to further strain relations between the former Soviet republic and the European Union.

Mr. Lukashenko has ruled his country with an iron fist for almost 18 years, keeping it out of the European mainstream. Minsk's relations with Brussels have reached an all-time low after Mr. Lukashenko's launched a crackdown on political opposition following mass protests against his re-election in December 2010.