The plane transporting Gotovina, who was arrested in the Canaries on Wednesday, will most likely take off from the military base Torrejon de Ardoz outside Madrid in the morning, the same source said.
"We will extradite him to the ICTY as soon as possible. This is related to issues of logistics and infrastructure," Spanish Interior Minister Jose Antonio Alonso said, congratulating the Spanish police on the arrest and noting that it was "good news for the international democratic community".
Alonso said the "two fake passports" in Gotovina's possession showed he had stayed in Argentina, Chile, Russia, China, the Czech Republic, Tahiti, and Mauritius.
The fake Croatian passport in the name of Kristijan Horvat, which Gotovina had on him when he was arrested in the Canaries on Wednesday evening, had entry and exit stamps of those countries. The last one, bearing the date November 25, was from the island of Mauritius, according to Alonso.
Gotovina, whom the International Criminal for the former Yugoslavia (ICTY) in The Hague suspects of war crimes committed during and after the 1995 Operation Storm, is currently detained in a prison near Madrid, awaiting transfer to the UN court's detention unit at Scheveningen.
A Spanish police unit specialised in tracking down fugitives has been tailing Gotovina since October, after Interpol said he might be in the Canaries, said Alonso.
On Wednesday evening, three Spanish police "spotted Gotovina having dinner with a male friend in a hotel" and called another six police to help them arrest him, the minister said, adding the police found in Gotovina's hotel room 12,000 euros in 24 EUR500 notes.
The Interpol arrest warrant for Gotovina is still in force, according to Interpol's website. The warrant was issued in August 2001 on the order of the Hague tribunal.