EU foreign policy chief Catherine Ashton says she is greatly concerned that the Iranian High Court has upheld the sentences of five Ahwazi Arab activists who could face imminent execution.
In a statement issued on January 29, Ashton also said she was concerned by reports the men did not receive a fair trial.
She urged the Iranian authorities to commute the sentences.
International human rights groups and United Nations' rights experts have also called on the Iranian authorities to cancel the activists' death sentences.
The five men were sentenced to death last year on terrorism-related charges because of their links to a banned cultural institute that promoted their Arab heritage.
They were arrested in early 2011 in their homes in the southwestern city of Ahwaz.
The High Court upheld their sentences last week.