Tata Tea is in talks with a Sri Lankan firm to sell its stake in a plantation venture here, officials said.Tata had invested in Sri Lanka through a joint venture with Watawala Plantations, which sells Ceylon tea under the brand names of Zesta and Watawala.Watawala's controlling shareholders signed an agreement with a Sri Lankan buyer yesterday to begin due diligence.The deal will be clinched after both sides are satisfied with the outcome of the due diligence, Watawala's CEO Vish Govindasamy said today."There is no time frame as to when the due diligence will be finished, but Tata had announced plans sometime back to gradually get out of plantation management," he said.Tea industry players are speculating that the buyer could be either Richard Pieris and Company or James Finlays. Conglomerate Richard Pieris has recently emerged as the biggest plantation owner.Last year, Tatas sold their Indian plantations by transferring tea estates to an employee-owned private company.Sri Lanka produces around 300 million kilos of tea each year of which around 10 million kilos comes from Watawala's estates comprising 12,442 hectares of estate land growing tea (41%), rubber (18%) and palm oil (8%).