BELGRADE, March 24 (Xinhua) -- A ceremony to mark the 16th anniversary of the beginning of the 1999 North Atlantic Treaty Organization's (NATO) bombings was held here on Tuesday.

The outdoor ceremony started at 7:58 p.m. local time, the beginning of the bombings 16 years ago. Air raid sirens and sound of bombings were heard in the centre of Belgrade, where bombing ruins of the two buildings of the former military headquarters that to this day face the Serbian government building.

According to police estimations, some 5,000 citizens attended the ceremony, who, together with state and military leaders, commemorated the event by honouring its numerous victims with a minute of silence.

Serbian Prime Minister Aleksandar Vucic said at the ceremony Serbia held its dignity and had no fear when facing with the attack by 19 countries and that it will not forget a single victim of the war.

"We are a small country, but strong and proud, home to people that cannot be conquered. We learnt our lessons and we will fight for a normal and dignified life as all civilized nations in Europe," Vucic said.

"We wish to have no conflicts with NATO as well as no one else, but we will be determined to keep our military neutrality", Vucic told a gathered crowd, adding that he wishes to join European Union as a proud country which is able to maintain its good relations with Russia as well as other eastern allies.

The 78-day long NATO campaign started on March 24, 1999 without the approval from the Security Council of the United Nations.