Poland filed an official complaint with Russian authorities due to an attack on a its diplomat in Moscow, demandinged better security for the embassy personnel.
The Polish Embassy in Moscow delivered a letter to the Russian Foreign Ministry demanding that the perpetrators of Wednesday's attack, the second in recent days, be brought to justice, Poland's consul general in Russia, Tomasz Klimanski, told TVN24 news channel in Moscow.
He said Russia needed to meet "the responsibilities which a host country has ... in ensuring security to the site as well as it's workers."
The Polish diplomat attacked on Wednesday sustained head and chest injuries, a torn ear and bruises. On Sunday, another member of the embassy staff was attacked about 60 meters (65 yards) from the building, suffering a concussion.
The incidents follow the July 31 mugging of three sons of Russian diplomats in a Warsaw park, during which the boys' cell phones were stolen.
Russian President Vladimir Putin's government demanded an apology, claiming anti-Russian attitudes had inspired the attack. The Polish Foreign Ministry expressed "deep regret," but said it owed no apology for what it said was a criminal act.
Warsaw police said Thursday they had arrested two people indirectly related to the mugging of the Russians.
The two were detained on suspicion that they receiving goods stolen during the attack, Warsaw police spokeswoman Anna Kedzierzawcka said.
"We are still looking for and trying to arrest as quickly as possible the perpetrators of the attack," Kedzierzawcka is quoted as saying by the AP.
The shooter freely entered the building of the university and opened fire at those who were present on the ground floor