HAVANA - Relatives of Cubans arrested during the largest demonstrations in decades across the island said that at least 57 protesters are scheduled to go on trial this week, some facing sentences of up to 30 years in prison.

The relatives told The Associated Press that three collective trials are scheduled, with 21 charged in the eastern city of Holguin, 20 in Havana and 16 in Santa Clara.

Officials initially appeared to be caught off guard when thousands of Cubans took to the streets in cities across the island on July 11 and 12 to protest shortages of goods, power blackouts and economic hardship - with some also calling for a change in government.

Cuban authorities acknowledged that some complaints were justified, but they said that the United States was the real force behind the protests, which appeared to have been mobilized in part via recently authorized social media networks.

At least one person died, and several shops and vehicles were vandalized or burned.

Officials have never given an official number of arrests during the protests, though court officials said in August there had been 23 quick trials of 67 defendants facing lesser charges such as public disorder.

Since then, prosecutors have formalized more serious charges, such as sedition, against other defendants, said Salome Garcia of Justice 11J - a group with members in Cuba and abroad that tries to track the cases of those detained.

The organization said it has confirmed 1,334 detentions, 223 convictions for various charges and 231 others facing charges. It said 98 people had been fined.

The group said the initial detainees included 48 people under the age of 18 - the age of criminal responsibility is 16 in Cuba - though several of them have since been freed.

Roxana Garcia, the sister of 24-year-old defendant Andy Dunier Garcia, said she had been told the trials are expected to last three to four days. Her brother is charged in Santa Clara with public disorder as well as attacking and contempt of authority.

She said the defense attorney seemed to be doing a good job and that the only witnesses against the defendants are 'the same police who beat them.'

In Havana, Yaquelin Cruz said her 20-year-old son, Dariel Cruz, faces a prosecution request for a 15-year-sentence for sedition - attempting to overthrow a legitimate government. She said her son recently was stabbed in prison.

Justice 11J's list of cases indicates some in Holguin face 30-year sentences for the same charge.

Several relatives said they had been informed that only one family member of each defendant would be allowed in the courtroom.

Government authorities did not immediately respond to requests for information on the cases.

The United States has denied mobilizing the protests and responded to Cuba's crackdown on the demonstrations by imposing sanctions on officials it says have been complicit in it.