Egypt's justice minister Tuesday returned a letter he received from the U.S. ambassador, who had asked Egypt to lift a travel ban on Americans working with pro-democracy groups in the country.

Justice Minister Adel Abdel-Hamid said the letter should have been addressed to the judges investigating the groups, and that only those subject to the ban had the right to raise the issue.

Egyptian parliamentary speaker Mohamed Saad al-Katatni called the letter unacceptable interference from the U.S. ambassador.

In Washington, U.S. State Department spokesman Mark Toner said the travel restrictions are unfair and onerous, and should be lifted immediately.

Egypt has barred a number of foreigners, including six Americans, from leaving the country. They include Sam LaHood — son of U.S. Transportation Secretary Ray LaHood.

Egyptian authorities say the foreigners cannot leave while officials investigate alleged criminal activities by non-governmental organizations working to support Egyptian elections.

The State Department says the NGOs are non-partisan and do not support or give money to any individual candidates.