Polish authorities said on Monday that Russia had detained four of its soldiers on suspicion of stealing credit cards from one of the victims of the plane crash that killed Poland's president and 95 others.
A representative of Russia's Interior Forces denied that any Interior Ministry servicemen had been detained. The Defence Ministry could not immediately be reached for comment.
Polish prosecutors have been investigating the theft of two credit cards that belonged to Andrzej Przewoznik, a historian who died when the presidential plane crashed in western Russia on April 10.
"I can confirm that we have been informed (by the Russian side) that four soldiers from the units that secured the crash area were detained," a spokeswoman for the Internal Security Agency (ABW) said.
Polish media have reported that 6,000 zlotys ($1,800) were withdrawn with one of Przewoznik's cards some two hours after the disaster.
Polish government spokesman, Pawel Gras had said on Sunday that Russia had arrested four policemen - rather than soldiers - over the alleged theft. Gras was not available on Monday.
Polish Acting President Bronislaw Komorowski asked Russian President Dmitry Medvedev last month to increase security around the sight of the plane crash near Smolensk after Polish reports showed victims' personal belongings unearthed there.
Local media also showed images of civilians collecting items near the wreckage of the plane soon after the accident.
The crash, in which the heads of Poland's armed forces, its central bank governor and many other senior officials were also killed, caused shock and grief in Russia as well as in Poland and raised hopes of better relations between the two countries.