Austrian Foreign Minister Ursula Plassnik, whose country holds the bloc's rotating Presidency, said EU countries would raise the issue with U.S. President George W. Bush at a summit in Vienna next week.
She said that for a country like the United States, "committed to freedom, to the rule of law and to due process, [Guantanamo] is an anomaly."
Plassnik was speaking to reporters after chairing a meeting of EU foreign ministers in Luxembourg, two days after the U.S. military reported the deaths of three detainees at Guantanamo Bay.
The military says the three men committed suicide. The U.S. military today released the names of the three detainees.
According to a statement, Saudi Arabians Mani Shaman Turki al-Habardi Al-Utaybi and Yassar Talal Al-Zahrani, along with the Yemeni Ali Abdullah Ahmed, were the prisoners who hung themselves by nooses made from sheets and clothing early June 10.
They are the first prisoners to die at Guantanamo since the United States began sending suspected Al-Qaeda and Taliban captives there in 2002.