CAIRO, May 31 (RIA Novosti) - Twenty-two Russian students are still being held in police custody in Egypt and the date of their release is unknown, Russian Vice-Consul in Cairo Timur Agametov said on Sunday.

"It is not known when they will be released. A corresponding note was sent to the Egyptian Foreign Ministry back on May 27 but we have not received any reply so far," the Russian diplomat said.

A group of foreign students, including 37 Russians, were detained early on Wednesday in a police raid on the Al Azhar University in Cairo.

Four Russians were released soon after the check of their documents while another 11 were set free after the Egyptian authorities got convinced that they studying in Egypt and had valid visas.