Blood will be available for veneration at John Paul II's beatification after being taken from pontiff as he lay dying

More than 50 heads of state and several hundred thousand pilgrims are expected in Rome for Pope John Paul II's beatification. Photograph: Plinio Lepri/AP

A phial filled with the blood of the late pope John Paul II will go on display at his beatification on Sunday and become available for veneration by the faithful.

The Vatican said the blood, which had been stored in a Rome hospital, had been kept in a liquid state by an anti-coagulant that was added when it was taken from him.

The Polish pontiff is to be beatified at a service celebrated by his successor, Benedict XVI. More than 50 heads of state and several hundred thousand pilgrims are expected in Rome for the occasion.

The Vatican said doctors had taken a quantity of blood from the pontiff while he lay dying, which had been sent in four containers to the blood transfusion centre at the Bambino Gesu hospital in Rome. Two "remained at the disposal" of his private secretary, Stanislaw Dziwisz, who was later made a cardinal and the archbishop of Krakow.

The remaining two phials stayed in the hospital where they were "devoutly safeguarded by the nuns" who work there as nurses. Both had been put into reliquaries: ornate relic containers that are usually made with precious metals and stones.

One of the reliquaries was to be returned to the hospital. The other would be exhibited on Sunday and then be kept with other relics in the Vatican.

Beatification is the final stage before canonisation, though not all those who are beatified – and are thereafter styled Blessed – are raised to sainthood.

Pope John Paul II is to be beatified barely six years after his death. He was fast-tracked after the Vatican accepted he was responsible for the miraculous cure of a French nun. One miracle is sufficient for beatification; two are required for canonisation.