By Charles Haviland
BBC News, Colombo
Campaigners say many tea workers live in poverty
Trade unions in Sri Lanka say a quarter of a million tea plantation workers have joined a non-cooperation exercise to lobby for higher wages.
Employers say they are concerned that production and exports will be affected.
Sri Lanka is the world's fourth biggest tea producer, after China, India and Kenya.
But a marked slowdown has now gripped its largest tea estates, most of which lie in the hills.
It is not a strike.
But three large trade unions have announced what they call a "non-cooperation exercise".
Workers are still picking the tea - but they are preventing it from leaving the plantations.
It is all to push for higher pay - they want to almost double the minimum daily wage to about $4.50 (£2.75).
"You see, the plantation workers are the people with the largest number in poverty," says Ramiah Yogarajan, national organiser for the Ceylon Workers' Congress, a political party which has traditionally represented Tamils working in the plantations.
"Since 1992 the plantation companies were privatised, and from 1992 to 2002 poverty in the plantations increased from 22% to 32%. So there is a serious issue in the income of the workers."
But the main tea traders' association has warned that both production and exports will be affected.
And the Employers' Federation of Ceylon has been writing to the unions, complaining at what it says are heavy-handed practices in imposing the non-cooperation.
The trade unions say they are pleased that business owners are sitting up and taking notice. The three unions leading the action say other unions are joining in.
Drought has severely affected recent tea crops and livelihoods here - and poverty-stricken workers are in the mood to take a stand.