Poland’s experts have voiced incomprehensible claims concerning some signs of an explosion on the fragments of the Polish presidential Tu-154M plane, which crashed near the Russian city of Smolensk in 2010, Russian Investigative Committee spokesperson Svetlana Petrenko said - TASS reported.

"It is absolutely unclear what the new conclusions drawn by the Polish experts are based on," she said. "Right after the crash, a ballistic teat and a blast assessment study were conducted, proving that the aircraft had not been affected by any explosives," Petrenko pointed out. "At the same time, Polish experts, including members of the new investigation commission, have not conducted any examinations of the aircraft fragments since 2014," she added.

According to the Russian Investigative Committee’s spokesperson, in 2011, after assessing all the available information, both Russian and Polish experts came to the conclusion that the crash was caused by the aircraft’s encounter with a birch tree. "The plane had remained intact until it bumped into the birch tree," Petrenko stressed adding that the aircraft fragments were kept in Russia as material evidence in the Investigative Committee’s criminal investigation.

Poland’s government sub-commission investigating into the Polish presidential plane crash earlier claimed to have found some signs of an explosion on the aircraft’s left wing.

"The destroyed left wing of the Tu-154M bears signs of an explosion," the sub-commission’s press service said in a statement commenting on its recent meeting held on July 25.

However, the statement does not elaborate whether any traces of explosives had been detected, nor does it make any assumptions as to what could have caused the possible explosion.