HAVANA (Reuters) - Cuban prosecutors are asking for a nine-year prison sentence for one of the country’s top opposition leaders Jose Daniel Ferrer on charges of assault, his wife Nelva Ortega said.

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

Ortega told Reuters she learned the news when she visited Ferrer on Thursday but that he received the documents in his case on Jan. 13. He has yet to stand trial, and the documents did not include a date for the proceedings, she said.

The Cuban government, which calls the 49-year-old Ferrer a U.S.-backed counterrevolutionary, declined to comment.

Authorities arrested Ferrer on Oct. 1 on the assault charges, which his relatives and his opposition organization, the Patriotic Union of Cuba (UNPACU), say was done to silence him.

International rights organizations including Amnesty International have described him as a prisoner of conscience and have campaigned for his release.

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, which has become one of Cuba’s largest and most active opposition organizations.

The Cuban government regularly detains rights activists for a few hours or days, in what the activists describe as a long-running campaign of harassment and repression.

But in recent years, it has become unusual for the authorities to arrest a prominent figure for more than a week.

Cuba does not usually comment on the detention of dissidents, which would give them more publicity.

But given the high profile nature of Ferrer’s case and the international campaign for his release, the government broadcast a special television report on him in November, in which he was denounced as aggressive and a liar.

Critics of the authorities in Havana say the government appears to be tightening control, fearing unrest over deepening economic woes following tighter U.S. sanctions, especially since internet service was expanded, increasing access to information and the ability to mobilize.