The formal decree requires the signature of Prime Minister Donald Tusk, a step expected to be completed shortly, according to the head of the Presidential International Policy Bureau, Wojciech Kolarski.
The pope died on Monday at 7:35 a.m. at the age of 88, following a stroke, coma and irreversible heart failure.
Francis, who was the first pope from the Americas, had battled serious respiratory problems.
He was hospitalized in Rome in February and March but appeared in public during Easter celebrations, including an unexpected tour of St. Peter’s Square in the popemobile.
Duda and First Lady Agata Kornhauser-Duda will attend the funeral in Rome.
Poland became the fourth European nation to declare official mourning following the announcement of similar gestures by Spain, Portugal and Malta, Polish state news agency PAP reported.
Italy has announced five days of mourning, and Argentina, the pope’s homeland, will observe a full week.
Several other countries, including East Timor, Panama, Costa Rica and Lebanon, have also declared periods of mourning.
Under Polish law, the president may declare national mourning through a decree. This can occur in response to the deaths of major domestic or international figures, natural disasters, terrorist attacks – especially if Polish citizens are among the victims – or the passing of individuals whose contributions were significant to the nation.
During periods of mourning in Poland, national flags on public buildings are flown at half-staff and adorned with black ribbons.
Public events such as concerts, sports matches, and entertainment programmes are typically cancelled or postponed.
National mourning has been declared numerous times in recent decades. These include the July 1997 "flood of the millennium" in southern Poland, the 9/11 attacks on America, which claimed five Polish lives, and the 2004 Madrid train bombings.
After the death of Pope John Paul II in 2005, Poland entered six days of mourning.
Following the 2010 Smolensk air disaster that killed President Lech Kaczyński, his wife Maria and 94 others, many of them senior officials and dignitaries, then-parliamentary Speaker Bronisław Komorowski, acting as head of state, declared over a week of mourning.
Other instances include the crash of a military aircraft near the northwestern town of Mirosławiec, a train collision near Szczekociny in southern Poland, a bus accident near Grenoble, France, and fatal incidents in Polish coal mines.
Poland has also declared mourning on the funerals of former prime ministers Tadeusz Mazowiecki and Jan Olszewski, as well as for Gdańsk Mayor Paweł Adamowicz, who was fatally stabbed during a public charity event in 2019.
While the law does not specify the length of national mourning, the duration is generally determined by the circumstances and cultural context.
(rt/gs)
Source: IAR, PAP