Four members of Aung San Suu Kyi’s opposition party have been sentenced to more than seven years in prison in secret trials in western Myanmar, a spokesman said Wednesday.

The four were arrested near the western port city of Sittwe, one of several places around the country where Buddhist monks led marches against the military government in the biggest pro-democracy protests in nearly 20 years.

“So far we have confirmation that four people were each sentenced to seven and a half years in prison. They were accused of taking a leading role in the monks’ protests” in Sittwe, said Han Thar Myint, spokesman for the National League for Democracy (NLD).

Among those sentenced was 85-year-old Kyaw Khine, the head of the NLD chapter in Taunggok township outside Sittwe, the spokesman said.

The three others were identified as Than Pe, Tun Kyi and Sein Kyaw.

Myanmar has admitted to arresting nearly 3,000 people over the protests, which were violently put down by soldiers and riot police in late September.

State media said Wednesday that 468 remain behind bars, but the four convicted in Sittwe are believed to be among the first formally sentenced to prison time.

“We will give them legal support,” Han Thar Myint said, adding that the NLD believes about 280 of its members are still detained.

Amnesty International and other human rights groups have voiced fears that the detainees could be tortured or suffer other abuses.

The United Nations has called for the release of all political prisoners. Most prominent among them is Aung San Suu Kyi, the Nobel peace laureate who has spent more than 12 of the last 18 years under house arrest.