The Cauvery Calling campaign collects donations online to plant 2.42bn trees along the banks of the Cauvery river.
Leonardo DiCaprio has been urged to withdraw support for a controversial tree-planting programme in India, which could result in catastrophic environmental damage.
An open letter, signed by more than 90 Indian environmental and rights groups, warned that the Hollywood actor and activist’s endorsement of the Cauvery Calling campaign was ill-advised.
DiCaprio posted an endorsement of the Cauvery Calling campaign on his Facebook page on Saturday, and his environmental charity Earth Sense has previously hosted the spiritual leader at an event in Los Angeles.