Greece's former king Constantine II, who has died aged 82, will have a private funeral next week and be buried at the former royal estate of Tatoi, his family and officials said Wednesday.

Constantine -- who died in an Athens hospital on Tuesday -- will be buried "near his ancestors in Tatoi" north of Athens, a government statement said.

"The ex-king will be buried as a private citizen," it added, following a special cabinet meeting chaired by Prime Minister Kyriakos Mitsotakis.

The funeral service will be held on Monday at the Athens Metropolitan Cathedral -- the site of his 1964 wedding -- Constantine's family said in a statement.

Most members of the former royal family are buried at the former royal summer palace at Tatoi, including the dynasty's Danish-born founder George I and another seven kings and queens of Greece.

The last member of a century-long dynasty, Constantine had reigned for just three years when a brutal army dictatorship seized control of the country in 1967.

Declassified US diplomatic cables say Constantine may have been mulling martial law himself prior to the coup.

Nearly eight months after the junta seized power, Constantine organised a military counter-coup that failed.

He fled to Rome with the rest of the royal family, and later to London.

The junta abolished the monarchy in 1973. After the restoration of democracy a year later, a public referendum voted not to restore the royal family.

Later locked in a bitter property dispute with the Greek state, Constantine had his Greek citizenship revoked in 1994.

The ex-king was a cousin of British monarch King Charles III, godfather to his heir Prince William and brother of Sofia, the mother of King Felipe VI of Spain.

Constantine was married to Anne-Marie -- sister to the Queen of Denmark Margrethe II -- and they had five children.

It was not immediately known which European royals would attend the funeral.

As crown prince, Constantine won a sailing gold medal in the 1960 Rome Olympics and was an honorary member of the International Olympic Committee.

The ex-king had returned to Greece in 2013, selling the 9,500-square-foot London mansion where his family had lived for four decades.

Still styling himself "king", he had battled poor health in recent years.

His death on Tuesday came exactly a century after that of his grandfather and namesake Constantine I.

In 2008, an opinion poll found fewer than 12 percent of Greeks favoured a return to a constitutional monarchy. More than 43 percent blamed the former king for the period of junta rule.