BELGRADE, Yugoslavia (AP) _ The crown prince of Yugoslavia's royal family, born in exile, received a jubilant welcome Saturday from tens of thousands of Serbs on his first visit to his ancestral land.

Many wept with joy and waved royal flags as they crowded the airport to catch a glimpse of Aleksandar Karadjordjevic, his wife and three sons, who arrived on a trip sponsored by Serbia's political opposition.

''Today is the happiest day of my life, I have returned to my fatherland,'' Karadjordjevic, speaking in halting Serbian, told a crowd of about 7,000 people at an airport ceremony.

He knelt to kiss a piece of turf brought from the royal family's native village of Topola and stood on it as a choir sang the royal anthem, ''God of Justice.''

Karadjordjevic, a former British army officer and a London businessman, wants Serbia to become a constitutional monarchy like Britain.

He said his visit is apolitical, but opponents of hard-line Serbian President Slobodan Milosevic and his Socialists thought the trip could help them.

''This visit has a political significance because his arrival reminds us of the democratic traditions of Serbia,'' said Vojislav Kostunica of the Democratic Party. ''We would not have organized it if we had not thought it would help us politically.''

The crowd chanted ''We Want the King'' and ''Kingdom of Serbia.'' When the public address system failed during Karadjordjevic's brief speech, the crowd blamed Milosevic and his Socialists, the former Communist Party.

''Red Bandits 3/8'' they chanted. ''Slobodan, Go Away.''

Karadjordjevic will attend a memorial service for his grandfather, Alexandar I, the Serb monarch who championed the union of Serbia, Croatia and Slovenia in one country that eventually became known as Yugoslavia.

The country now is disintegrating in a violent struggle on Croatian soil.

The monarchy was abolished and a Communist republic was declared in 1945. Karadjordjevic was born that year in London's Claridge's Hotel, where his parents' suite was proclaimed Yugoslav territory to conform with a law that the heir to the crown must be born in Yugoslavia.