Bulgaria will mourn the casualties of the Smolensk plane crash on April 18, Sunday, the day of the funeral of late Polish President Lech Kaczynski.

Bulgaria's governmental press office announced Friday that Sunday will be a national mourning day in the country.

On April 18, the national flags of Bulgarian governmental institutions and embassies will be flown at half mast. Bulgaria's government has also appealed to the public to be sympathetic with the tragedy of the Polish people and to abstain from holding any celebrations on the day in question.

The funeral of President Lech Kaczynski and his wife Maria Kaczynska, who last week perished together with 94 other people, mostly high-ranking state officials in a TU -154 plane crash in Smolensk, Russia, will be held on Sunday in the Polish city of Krakow.

However, Kaczynski's burial may be delayed due to the huge ash cloud caused by the eruption of a volcano in Iceland and passing over Northern Europe that has led to the cancellation of flights throughout Europe, including Warsaw airport.

Despite protests over Kaczynski's final resting place, it has been decided that the president will be buried alongside monarchs and national icons in the Wawel Cathedral in Krakow.

The Cathedral also holds the remains of major historical figures like Marshal Jozef Pilsudski, the post-World War I leader of Poland, and Gen. Wladyslaw Sikorski, leader of the government-in-exile during World War II.

On Saturday, April 10, 2010, a total of 96 people perished, including President Lech Kaczynski as a Polish government plane Tu-154 crashed near Smolensk, Russia, en route to the remembrance ceremonies for the 70th year since the Katyn Massacre.