The mayor of the Polish port city of Gdansk died on Monday, a day after a knife-wielding assailant stabbed him in the heart in front of hundreds of people at a charity event, local media reported.

Gdansk's Mayor Pawel Adamowicz speaks during the 27th Grand Finale of the Great Orchestra of Christmas Charity in Gdansk, Poland January 13, 2019. (Photo: VCG)

"Despite all our efforts, we failed to save him," Doctor Tomasz Stefaniak, director of Gdansk's University hospital said, quoted by the Polish PAP news agency.

The mayor of Gdansk Pawel Adamowicz died on Monday following a stabbing attack at a charity event, Poland's Health Minister Lukasz Szumowski said. (Video source: AP)

Anti-violence rallies are being planned nationwide after Sunday's shock attack on Mayor Pawel Adamowicz.