By Marcin Goclowski and Wojciech Zurawski
WARSAW/KRAKOW, Poland (Reuters) - Poland's ruling nationalists held scaled-down events on Friday to commemorate the 10th anniversary of a plane crash in Russia that killed top politicians and military officers, and they renewed criticism of Moscow's handling of the disaster.
Senior officials laid wreaths at a monument in the capital Warsaw to honour late president Lech Kaczynski who died in the crash. They walked in single file, guarded by police wearing surgical masks to protect them from the coronavirus pandemic.
The crash in thick fog near Smolensk in western Russia was Poland's worst air disaster since World War Two and stunned the country. It also deepened political divisions and revived suspicions about Russia, Warsaw's former Cold War master.
President Andrzej Duda, an ally of the ruling Law and Justice Party (PiS) which was founded by Kaczynski and twin brother Jaroslaw, expressed regret that the coronavirus outbreak in Poland made it impossible to mark the tragedy properly.
Many Poles, including Duda, suspect that the crash was not caused by pilot error, as concluded in an official investigation by Poland's previous centrist government, but by foul play.
"After 10 years, it's difficult to say anything or predict whether the case can ever be resolved," Duda said in Krakow after visiting Kaczynski's grave in a crypt in Wawel cathedral.
"We don't have basic evidence, the wreckage is still in Russia, the black boxes are still in Russia."
Poland's foreign ministry said in a statement that it had renewed demands that Moscow returned the wreckage of the ageing Tupolev aircraft.
"There are no provisions in international law that allow Russia to withhold Polish property," it said.
Critics, including opposition politicians, accused PiS officials of flouting coronavirus restrictions that limit public gatherings and have left many cemeteries in the country closed to the public.
"This is not all right. With all certainty there was a way to mark today's anniversary by following the rules that all Poles must follow, and that Poles pay fines for breaking," said Jan Grabiec, spokesman for centrist opposition party Civic Platform (PO).
Russian authorities said on Friday there was no evidence of an explosion on board the plane, as some in Poland allege.
Russia's Investigative Committee said in a statement that crew errors led to the accident.
"The aircraft collided with a tree trunk at a height of about 11 meters," it said. "As a result of the detachment of part of a wing, the aircraft began to rotate and after a few seconds fell to the ground in an upside down position."
PiS has used the crash as a central plank of its campaign against the centrist PO, which ruled Poland for eight years until 2015.
It believes the party, led then by former European Council President Donald Tusk, obstructed the probe into the disaster.
Several officials from the prime minister's office at the time of the crash were also sentenced in 2019 for neglect of duty when organising the flight.
Tusk, who now heads the centre-right European People's Party, a pan-European umbrella group, accuses PiS of fomenting hatred towards his supporters and exacerbating political rifts in Poland.
(additional reporting by Joanna Plucinska in Warsaw, Anton Kolodyazhnyy in Moscow; Writing by Justyna Pawlak; Editing by Mike Collett-White and Hugh Lawson)