HANOI, Vietnam (AP) — A Vietnamese court has begun the trial of 22 democracy activists on charges of plotting to overthrow the Communist government in one of the biggest such trials in years.

A court official in central Phu Yen province says the defendants appeared in court Monday. The official didn’t give his name, citing government policy.

He says the trial could last five days.

State-controlled media have quoted the indictment as saying the group operated under the cover of an ecotourism company. The media say the group allegedly authored documents that distorted Communist Party policies to create distrust.

The government appears to be stepping up its campaign on dissidents despite criticism from Western governments.