HAVANA (Reuters) - One of Communist-run Cuba’s leading dissidents, Jose Daniel Ferrer, was due to go on trial on Wednesday on charges of abducting and assaulting a man, his supporters said, in a controversial case that is being closely watched worldwide.

FILE PHOTO: Jose Daniel Ferrer, who leads the Patriotic Union of Cuba (UNPACU), the country's largest dissident group, holds up a t-shirt with the writing "God, Fatherland, Freedom" in Palmarito de Cauto, Cuba, March 25, 2012. REUTERS/Mariana Bazo/File Photo/File Photo

The Cuban government has not confirmed that Ferrer was going on trial, but it has confirmed that he was arrested and is in jail. European officials, Amnesty International and the U.S. Embassy in Havana have said they will be watching the trial.

Ferrer, 49, is the leader of the Patriotic Union of Cuba (UNPACU), one of the country’s largest and most active opposition groups. The government calls him a U.S.-financed counterrevolutionary but said he was not jailed for his political views. It accused him instead of being a violent common criminal who kidnapped a man and caused him serious injuries last September.

Supporters of Ferrer, who was arrested last Oct. 1, say the charges are false and merely an attempt to silence a vocal critic. They say the trial - which foreign media have not been invited to cover - is a sham.

The case has garnered international attention, with global rights organizations, the European Parliament and the U.S. government calling for Ferrer’s release.

“It cannot be a crime to criticize policies that have set Cuba’s development tumbling backwards for the past 61 years,” U.S. Secretary of State Mike Pompeo wrote in an open letter to his Cuban counterpart Bruno Rodriguez on Monday.

Cuban official media on Wednesday did not mention the trial, which Ferrer’s supporters say is taking place in his hometown Santiago de Cuba, around 500 miles east of Havana.

The lawyer assigned to the activist by the state informed Ferrer’s wife Nelva Ortega late on Tuesday that the trial would start on Wednesday at 0830, according to Ferrer’s sister Ana Belkis Ferrer. Ortega could not immediately be reached for comment.

Ferrer’s sister, who lives in the United States, told Reuters she had been keeping in touch with Ortega and UNPACU members by phone, but their lines appeared to have been cut on Wednesday.

“Very early in the morning, they told me the courthouse had been besieged by security agents,” she said.

Ferrer was one of 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.

In recent years, it had become unusual for the authorities to arrest a prominent dissident figure for more than a week, although they continued to regularly detain rights activists for a few hours or days.

Ferrer’s case underscores an increase in repression of late, government critics say, likely related to increased U.S. hostility under President Donald Trump and deepening of Cuba’s economic problems.

Cuba and its arch-nemisis the United States had undergone a detente in 2014-2016 during the administration former U.S. President Barack Obama.