(Reuters) - A former senior official in the Armenian administration of Nagorno-Karabakh, detained since last September in Azerbaijan, has been persuaded to end a hunger strike, his family said on Thursday.

Ruben Vardanyan, an Armenian-born billionaire banker who made his fortune in Russia, was head of the Karabakh Armenian government from November 2022 to February 2023.

Vardanyan, 55, was arrested by Azerbaijani forces in September 2023, along with several other senior Karabakh officials while attempting to cross into Armenia.

"Ruben Vardanyan's family at long last managed to persuade him to end his hunger strike as his health and his conditions of detention have worsened," the family said in a statement on Vardanyan's Telegram channel.

"During a short conversation, family members told him about the growing pressure on Azerbaijan from the representatives of different countries."

The statement also said Vardanyan had been able to speak to his wife for the first time since he was detained. He had been allowed to make two calls since announcing he was going on hunger strike on April 5, the statement said.

Karabakh was the focal point of three decades of dispute and two wars between Azerbaijan and Armenia.

Long recognised as part of Azerbaijan, the territory came under the administration of the region's ethnic Armenian leaders in the 1990s, but was over-run by Azerbaijan's military after a lightning offensive last September.

Almost its entire population of about 100,000, mostly ethnic Armenians, fled to Armenia.

Those held by Azerbaijan include three former presidents of the breakaway region, a general in its army, the speaker of its parliament and its foreign minister.

Vardanyan has been charged with offences including financing terrorism and illegal border crossing. His family denies the allegations and demands that his trial, when it happens, should be open to international observers and the media.

"We have made it plain to Azerbaijan that world attention is focused on the fate of Armenian detainees, including my father," Vardanyan's son David said in the statement.

"I hope that growing interest throughout the world will lead to him and the others being released."

(Reporting by Ron Popeski; editing by Jonathan Oatis)