The Office issued the news of the detention and the investigation also on its web site, citing the suspect's initials and nickname and year of birth.
According to the Office, detention has been set so that an international arrest warrant could be issued. The suspect is not within reach of Croatian judicial bodies and such a warrant may be issued only following a detention decision.
The investigation was requested by the Sibenik County Prosecutor's Office, which accuses Vasiljkovic, 51, of acting contrary to Geneva conventions as commander of a special Serb paramilitary unit.
Vasiljkovic is suspected of torturing and killing imprisoned Croatian soldiers and police in a Knin prison in June and July 1991, and at Bruska near Benkovac in February 1993.
According to the charges, in Glina in July 1991, in his capacity as special unit commander, Vasiljkovic drew up a plan to assault and seize the police station in Glina, its suburb of Jukinac and the villages of Gornji Vudisevac and Donji Vidusevac.
During the attack, contrary to Geneva conventions, civilian buildings were demolished and destroyed, the population was forced to flee, their property was plundered, and civilians were killed and wounded, including a foreign journalist.
Charges against Vasiljkovic, an Australian Serb, were pressed after an Australian newspaper published a story about him in early September.
The Croatian justice minister said on that occasion that an investigation against Vasiljkovic had been launched in the past but was discontinued when the 1997 general amnesty law went into force.