THE LIBERAL mayor of the Polish port city of Gdansk has died after he was stabbed during a charity event by an ex-convict who stormed on stage and said it was revenge against a political party the politician once belonged to.

Pawel Adamowicz, 53, died as a result of wounds to the heart and abdomen in spite of efforts to save him that involved a five-hour operation and blood transfusions, health minister Lukasz Szumowski said.

“The fight for his life has been lost,” Szumowski confirmed.

The killing of Adamowicz (pictured left), a six-term mayor who often mingled freely with citizens of his city, sent Poland into shock.

Even before his death was announced, rallies against violence were being planned to take place across Poland, while in Gdansk, the city flag was lowered to half-mast and a Mass was planned.

The right-wing ruling Law and Justice party faced accusations from its critics that an atmosphere of hatred against Adamowicz and other liberal political opponents helped instigate the attack.

Government officials appeared to push back against that accusation, strongly denouncing the attack and stressing that the 27-year-old perpetrator had a history of violent bank robberies and possible mental illness.

The ex-convict who rushed on to the stage with a knife on Sunday and stabbed Adamowicz shouted that it was revenge against Civic Platform, which the politician belonged to for many years.

Donald Tusk’s aide said the top European Union official is travelling to his birthplace of Gdansk after the death of his friend.

Tusk, a former Polish prime minister, is the founder of Civic Platform and now president of the European Council.

He tweeted: “Pawel Adamowicz, Mayor of Gdansk, a man of Solidarity and freedom, a European, my good friend, has been murdered. May he rest in peace.”

Deputy chief prosecutor Krzysztof Sierak said there are “doubts” as to the mental state of the attacker, who used a 14.5cm (5.5in) knife in the attack on Adamowicz, and that two psychiatrists will examine him.

He had served five-and-a-half years in prison and was released towards the end of last year.

Yesterday, he was charged with murder.

Adamowicz was the city’s mayor for more than 20 years.

Thousands attended vigils across Poland last night, including in Gdansk.

Polish President Andrzej Duda described the attack as an "evil hard to imagine".

He said the day of the politician's funeral would be observed as a day of national mourning.

The mayor was attending the Great Orchestra of Christmas charity - an annual event where volunteers raise money for medical equipment in hospitals.