The Russian ambassador to Poland was doused in a red substance on Monday by people protesting against the war in Ukraine as he went to lay flowers at the Soviet Military Cemetery in Warsaw to mark the 77th anniversary of the victory over Nazi Germany.

The war in Ukraine has cast a shadow over this year's Victory Day, when Moscow honours the 27 million Soviet citizens who lost their lives in World War 2. Poland, a strong supporter of Ukraine in its resistance to Russia's invasion, opposed any large-scale commemoration taking place.

Video footage posted on Twitter showed the protesters, some with Ukrainian flags, surrounding the Russian delegation and chanting “fascists” before the ambassador was doused in the red substance.

Ambassador Sergey Andreev told reporters he and his team were not seriously hurt in the incident, TASS news agency reported.

“We will make a formal protest,” he said. “When they recommended that we not hold a larger event, we met them halfway, we didn't aggravate the situation.”

Earlier in the day the words “Kill Putin” were found written in blue and yellow, the colours of the Ukrainian flag, on a monument at the cemetry, private broadcaster TVN24 reported. The writing was later removed.

One protester interviewed by TVN24 said it was good that the ambassador had been covered in red.

“With all our heart we are with Mariupol,” she said, referring to the southeastern Ukrainian city that has been devastated by the war.

More than three million Ukrainians have fled to Poland since the war started on Feb. 24.

Poland, home of the Solidarity trade union that played a key role in bringing down communism in central and Eastern Europe, has long had a tense relationship with Russia and is an advocate of tough sanctions against Moscow over its invasion of Ukraine.

Russian President Vladimir Putin sent his troops into Ukraine on what he calls a “special military operation” to demilitarise and “denazify” Ukraine. Ukraine and the West say Putin launched an unprovoked war of aggression.

A Polish foreign ministry spokesperson said he had no immediate comment on the incident. A police spokesperson could not immediately be reached for comment

Reuters