Four ex-leaders of Azerbaijan's formerly ethnic Armenian-controlled region of Nagorno-Karabakh have been detained by Azerbaijan's State Security Service and taken to the capital Baku, the state-run Azerbaijani Press Agency (APA) reported on Tuesday.

However, three other former leaders of Karabakh have arrived safely in Armenia, the Armenian state news agency Armenpress quoted one of the three as saying.

Azerbaijan took control of Nagorno-Karabakh after three decades in a lightning military operation on Sept. 20, and vowed to prosecute the "criminal" separatist leadership, who it said had poisoned the minds of the population.

Almost all the 120,000 or so inhabitants of Karabakh have since fled to Armenia, fearing for their safety. But Azerbaijan has arrested Ruben Vardanyan, a former head of Karabakh's government, and Levon Mnatsakanyan, former commander of Nagorno-Karabakh's separatist army, at border checkpoints.

On Tuesday, APA said three former self-styled presidents of Nagorno-Karabakh, Arkady Gukasyan, Bako Sahakyan and Araik Arutyunyan, as well as ex-parliamentary speaker David Ishkhanyan, had been arrested.

However, former state minister Artur Arutyunyan, ex-interior minister Karen Sarkisyan and the former head of Karabakh's security service, Ararat Melkunyan, all entered Armenia on Tuesday, Artur Arutyunyan said, according to Armenpress.

Karabakh is viewed internationally as part of Azerbaijan but had been run as a breakaway ethnic Armenian statelet since the 1990s following the collapse of the Soviet Union.