CAIRO, July 20 (Aswat Masriya) Egyptian President Abdel Fattah al-Sisi has announced  a three-day period of mourning for the 21 soldiers killed on Saturday in the New Valley, a presidential statement said. 

"The mourning period starts on Sunday in all of Egypt for the martyrs of the nations,"  the statement added. 

Smugglers killed 21 soldiers in an attack on a military checkpoint in New Valley's Farafra Oasis on Saturday evening, according to an Armed Forces statement.

The statement described the attack, which occurred near the Egyptian-Libyan borders, as "terrorist".