The remains of 431 Soviet army soldiers killed during a World War II battle in Poland were reburied over the weekend, Russian military officials said.

Vyacheslav Polovinkin, the head of the Russian Defense Ministry office in charge of military memorials in Poland, said the remains of the Soviet soldiers killed during the 1945 Siege of Kustrin in western Poland were laid to rest Sunday at an army memorial cemetery at Cybinka, Poland, RIA Novosti reported.

The remains had been exhumed from a 1950s mass grave near the battle site at Kustrin -- what is now called Kostrzyn-on-the-Oder -- after months of painstaking work.

The Soviet soldiers fell during an Eastern Front battle in the final months of World War II at Kustrin, about 50 miles from Berlin. It was one of the final roadblocks between the advancing Soviets and the German capital.

German troops turned the industrial town into a powerful fortified area meant to prevent the advance of Soviet troops to Berlin. The city was severely damaged during the 1945 assault.

A 2011 book about the battle, "The Siege of Kustrin" by British author Tony Le Tissier, said the Germans defended the outpost tenaciously, sending high school students and elderly men to fight against the Soviet soldiers. The Germans were driven from Kustrin after a 60-day siege that resulted in thousands of casualties on both sides.

After its capture, Soviet troops killed in the siege were buried in several mass graves. In 1953, the remains of the soldiers were transferred to a military cemetery near Kostrzyn but over the years it had become clear the work had been carried out hastily and the identities of the soldiers were lost.

Late last year, Polish researchers found the remains of more than 100 soldiers and work continued this spring when more than 300 more remains were found.

The Polish historical group Witez carried out the exhumation work with the help of domestic and foreign volunteers from Russia, Lithuania, Ukraine and Germany, its director, Julian Wierzbowski, told the Polish news agency PAP.

In one of the graves, which contained the remains of 40 soldiers, volunteers found a medal for bravery. The number stamped on it could help officials establish the identity of its owner and that could yield clues to the identities of others buried at the site.

Work on the exhumations is expected to be competed in fall.

Sunday's reburial in Cybinka was preceded by a short service performed by the Orthodox parish in Torzym. It was attended by representatives of the Russian, Belarusian and Kazakh embassies, the news agency reported.

Before World War II, the military cemetery in Kostrzyn was a German sports stadium but over the decades became forgotten and is covered by forest, with its only remaining monument an entrance gate.

Wierzbowski told the Polish newspaper Gazeta Lubuska remains found were mostly incomplete skeletons, which often lacked the head, but there were exceptions in which the remains of several soldiers had been preserved in their entirety.

"Some of the people had with them small personal items like knives, razors or medallions," he said.

Krzysztof Socha, an archaeologist at the Museum of the Kostrzyn Fortress, added some of the bodies had amputated limbs while others were charred, indicating they had died in fires.