Fair trade campaigners have held a demo in London, demanding tea firms end a "crisis" engulfing the Indian industry.
The charity protested as part of its 'stop corporate abuse' campaign
ActionAid launched the protest outside the annual general meeting of Unilever, which makes Brooke Bond and PG Tips.
The charity says the company is profiting from worsening conditions and falling prices on Indian plantations.
Unilever, the world's largest tea buyer, says it has had "amicable and productive" dialogue with ActionAid and is studying their latest claims.
The protest comes amid reports of increasing problems on Indian plantations.
Attacks against estate owners and managers by workers are on the rise, says the BBC's correspondent in Calcutta, Subir Bhaumik.
A drop in demand and falling prices have lead to many workers being laid off and wages going unpaid, fuelling violence in Assam and West Bengal, our correspondent says.
Reuters news agency has reported at least seven plantation bosses have been lynched or burned alive since December in Assam state alone.
ActionAid, in a report it has produced to accompany its protest, accused a Unilever subsidiary, Hindustan Lever, of "benefiting enormously" from the steep fall in prices.
It is calling on the company to produce all of its tea in line with fair trade principles, and to respect workers' rights in the same way it respects its shareholders' desire for profit.
The charity's spokeswoman Hannah Crabtree said the government should force companies to do this through legislation.
"Corporate social responsibility is not working. We want national and international legislation to control multi-national corporations," she said.
A spokesman for Unilever said ActionAid had produced a report in January, and both parties had had a productive meeting to discuss the claims it contained.
He added: "This latest report only came out last night. We are taking a bit of time to delve into it and find out what it is all about."
Although the charity said its aim was not to launch a boycott of Unilever products, it said UK consumers could help the situation by buying tea with the Fairtrade stamp on it.
India is the world's largest tea producer, with Assam accounting for about 55% of its 856m kilogram production last year.
But the £800m industry has been facing a crisis with prices dropping in weekly auctions, export figures slumping and domestic consumption also on the slide.
The slump has led to the closure of 20 tea estates and has left thousands of workers jobless.