BRUSSELS (Reuters) - The European Union's foreign policy chief Catherine Ashton called on Iran on Tuesday to halt the execution of five members of the country's Arab minority.

Ashton, who is in charge of negotiations between six world powers and Iran over Tehran's disputed nuclear program, said she was concerned about reports the five men had not received a fair trial and had been forced to confess.

"Reports that the executions of these men are imminent are very worrying, and I urge the Iranian authorities to commute the sentences," she said in a statement.

London-based Amnesty International and Human Rights Watch, which is based in New York, said last week that the men had been sentenced last year on terrorism-related charges because of their links to a banned cultural institute that promoted their Arab heritage. Their death sentences were upheld earlier this month.

The European Union is an active opponent of the death penalty worldwide, but has been especially critical of Iran's human rights record.

In 2011, the 27-member bloc enacted sanctions against Iranian officials it said were responsible for human rights violations.

(Reporting by Ethan Bilby; Editing by Rex Merrifield/Catherine Evans)