Polish President Lech Kaczynski declared three days of mourning Thursday after rescuers recovered the body of the last victim of a mine accident that killed 23 men.

The miners were killed by an explosion Tuesday more than 900 metres underground at the Halemba mine in southern Poland.

Family members of miners killed by a methane blast pray at the Helamba coal mine in Ruda Slaska.
(Irek Dorozanski/Associated Press)

"This brings to an end this very sad day," Zbigniew Madej, spokesman for the state-run Coal Co., said at the scene. "Nobody has a sense of relief, but rather a great weight on their heart."

Six bodies were recovered shortly after the explosion, and the remaining 17 were located after rescue efforts resumed Wednesday night.

Officials said all of the miners likely died in the initial blast.

Condolences arrived from world leaders, including German Chancellor Angela Merkel and Pope Benedict XVI.

"The Pope entrusts the souls of the dead to God's mercy, asking him to accept the offer of their toil and their life," the message from the Vatican said.

Methane gas made search difficult

The search for the missing miners had to be put on hold for most of the day Wednesday when teams encountered high concentrations of methane gas that they feared might cause a second explosion.

The search resumed shortly before midnight and the rescue teams found the bodies after digging through hundreds of metres of rubble for more than three hours, Madej said.

The methane gas explosion also would have produced extremely high temperatures, Madej said.

It may take some time to determine whether the miners were killed in the initial blast, by the cave-ins, or whether they died afterward, rescue officials said.

Kaczynski has pledged a full investigation, after surveying the site on Wednesday and meeting with grieving family members. The government has also promised financial assistance for the bereaved and a review of safety at all Polish mines.

Quest to retrieve gear ends tragically

The miners, who ranged in age from 21 to 59, were attempting to retrieve $23 million worth of equipment from a shaft that had been closed in March because of dangerously high gas concentrations.

Labour unions complain that a lack of investment and massive layoffs in recent years have resulted in falling safety standards at the nation's mines.

The nearly 50-year-old Halemba mine, located in the heart of the Silesia industrial region, is one of the oldest in Poland, and has a record of serious accidents.

In 1990, 19 miners were killed and 20 injured in a gas explosion at the mine. In 1991, five miners were killed in a cave-in.

Poland's worst mining accidents were in 1974 and 1979, when explosions killed 34 miners each at the Czechowice-Dziedzice in Silesia and the Dymitrow mine in Bytom.