On June 5, the head of the separatist regime in Nagorno Karabakh Bako Saakyan received the world-famous opera singer Montserrat Caballe, the Armenian media reported.

Caballe's concert in Yerevan will take place on June 9 at the National Academic Theater of Opera and Ballet.

Azerbaijani Foreign Ministry has repeatedly stated that such visits conducted without prior notification of the appropriate authorities of the Republic of Azerbaijan are illegal and damaging to the settlement process of the Nagorno-Karabakh conflict.

The conflict between the two South Caucasus countries began in 1988 when Armenia made territorial claims against Azerbaijan. Armenian armed forces have occupied 20 per cent of Azerbaijan since 1992, including the Nagorno-Karabakh region and seven surrounding districts.

Azerbaijan and Armenia signed a ceasefire agreement in 1994. The co-chairs of the OSCE Minsk Group, Russia, France and the U.S. are currently holding peace negotiations.

Armenia has not yet implemented the U.N. Security Council's four resolutions on the liberation of the Nagorno-Karabakh and the surrounding regions.