"I would like to ask the Serbian nation for forgiveness," the 76-year-old politician said during a meeting with his Serbian counterpart Aleksandar Vucic.

The Serbian president thanked Zeman for his gesture.

Back in 1999, Zeman supported the air strikes when he was prime minister of the Czech Republic.

The president said it is a trauma for him, from which he wants to free himself by apologising.

The NATO raids started shortly after the Czech Republic joined the military alliance in March 1999.

NATO carried out air raids on what was then the Federal Republic of Yugoslavia to precipitate the end of the war in Kosovo.

The assessment of the mission is still controversial today as it was not covered by a United Nations mandate.

As president, Zeman has predominantly ceremonial duties but he is considered an important opinion maker in his country.

Australian Associated Press