HAVANA (Reuters) - Amnesty International on Tuesday demanded the Cuban government explain the charges against the head of the country’s largest opposition group, whom Havana arrested a week ago, or release him from jail.

FILE PHOTO: Jose Daniel Ferrer (R), who leads the Patriotic Union of Cuba (UNPACU), the country's largest dissident group, sits at UNPACU's headquarter in Santiago de Cuba, Cuba, December 2, 2016. REUTERS/Sarah Marsh

Jose Daniel Ferrer, leader of the Patriotic Union of Cuba (UNPACU), was detained in the eastern city of Santiago de Cuba on Oct. 1 after a police raid on his home which also serves as the group’s headquarters, UNPACU activists told Reuters.

“Cuban authorities have imprisoned, harassed and intimidated José Daniel Ferrer García for more than a decade due to his political activism,” Amnesty said, recalling that he was held incommunicado for more than 10 days last year.

Ferrer should be informed of the charges or otherwise released, have access to lawyers and medical care and be able to communicate with his family, Amnesty said.

Ferrer was one of the 75 dissidents arrested in 2003 during a nationwide crackdown known as the Black Spring. He was released on parole in 2011 and soon after formed UNPACU.

Ferrer’s partner, Nelva Ismarays Ortega, said that during a visit Ferrer told her police threatened to charge him with a fabricated common crime so he would not be heralded as a political prisoner.

“They told him they were fed up with his activism ... and that they were very uncomfortable with how he’d supported the measures of the U.S. government against the Castro regime,” Ortega told Reuters by phone.

Ortega said authorities would not allow her to give Ferrer his medication for conditions such as the chronic gastroenteritis developed during his eight years in jail.

“He was in a lot of pain,” she said. “But he said he wasn’t afraid, and he was prepared to spend more years in jail as long as the truth were known.”

Cuba’s Communist government, which did not immediately respond to a request for comment, does not discuss police activity such as the detention of dissidents, whom it dismisses as provocateurs financed by the United States.

The government regularly detains them for a few hours or days, in what rights activists describe as a long-running campaign of harassment and repression. But a detention of more than a week is unusual, especially for a prominent figure.

Critics say the government appears to be tightening control, fearing unrest over deepening economic woes especially since internet service was expanded, increasing access to information and the ability to mobilize.