Villagers say their livelihoods there are being threatened by continuous government concessions to private rubber and other companies.
More than 100 villagers from rural areas detained by authorities in Phnom Penh after handing out leaflets detailing land concessions.
The garment sector provides around 300,000 jobs and more than $2 billion a year in exports.
Prime Minister Hun Sen signed a subdecree giving 1,000 families still living near the lake approximately 12 hectares of land.
Some 4,000 families are expected to be pushed from the Phnom Penh lake, which has been filled in almost to completion by Shukaku, Inc.
Former refugees at the congress said they wanted to share in the freedoms they were given.
The Diamond Bridge stampede was the worst disaster in Cambodia’s modern history, leaving 354 dead and 393 seriously injured.
Cambodia exports labor to Japan, Malaysia, South Korea and Thailand especially.
Two years ago, the Boeung Kak lake area in central Phnom Penh was home to 4,000 families.
Land disputes continue to be an ongoing problem for many Cambodians, who settled on land after the Khmer Rouge era.
The union was planning to demonstrate against rising prices of food, fuel and other living expenses.
The 58-article law was sent to the Council of Ministers for approval last week, after which it will pass to the National Assembly.