London: Unilever, the maker of Lipton, plans to buy all of its tea from sustainable, ethical sources to protect crops and improve conditions for plantation workers.

The company aims to have all Lipton Yellow Label and PG Tips bags sold in Western Europe contain tea certified by the Rainforest Alliance, a global environmental organization, by 2010, according to a statement on its website on Sunday. It plans to have all Lipton tea bags sold worldwide certified by 2015.

“This decision will transform the tea industry which has been suffering for many years from oversupply and underperformance,” Unilever chief executive Patrick Cescau said in a press release.

Unilever, based in London and Rotterdam, is the world’s biggest buyer of black tea; it said it currently buys about 12% of the world’s black tea supply.

Lipton is the world’s best-selling tea brand, and PG Tips is the UK’s top seller, according to the company. Unilever expects to pay farmers about €2 million (Rs10.8 crore) more for its tea by 2010 and €5 million more by 2015.

The first farm to apply for certification was Unilever’s own tea estate in Kericho, Kenya, the company said. Other facilities in Kenya, Tanzania, Malawi, Indonesia, India, Argentina and Sri Lanka will follow. Eventually the certification will extend to thousands of farms, the company said.

The first certified tea will be available to restaurants and caterers in Europe in August, Unilever said.

Rainforest Alliance, based in New York, is an international, independent, non-governmental organization. Its certification requires three levels of sustainability—worker welfare, farm management and environmental protection.

It certifies coffee, chocolate and bananas in products valued at more than $1 billion a year, including brands such as Starbucks Corp. and McDonald’s Corp., according to Unilever. BLOOMBERG

Reuters contributed to this story.