A staff member of global campaign group Greenpeace has been prevented from entering India and sent back to Australia, the group has alleged.
Aaron Gray-Block was refused entry on Saturday night despite having a valid business visa and all necessary documents, the group said.
It added that no formal reason was given by immigration officials and he was not officially deported.
A senior government spokesman said officials were looking into the matter.
KS Dhatwalia told the AFP news agency that officials had seen the media reports of the alleged incident.
Greenpeace said Aaron Gray-Block was on his way to meetings in India when immigration officials stopped him at Bangalore airport on Saturday night and put him on a flight to Kuala Lumpur without explanation.
His passport was seized and returned to him once he landed in the Malaysian capital, the environmental group said in a statement.
“Our colleague has a valid business visa, and yet he was prevented from entering India with no reason given,” Divya Raghunandan, programme director of Greenpeace India, said.
“We are forced to wonder if all international staff of Greenpeace will now be prevented from entering the country?”
Greenpeace has been involved in a long-running dispute with the Indian authorities.
In April, India blocked the group’s bank accounts, accusing it of violating tax laws and working against its economic interests.
In a major victory for the environmental group, the Delhi high court ordered the government to unfreeze two Greenpeace bank accounts last month.
Greenpeace, which has been present in India for 14 years and employs 340 people, says it has been targeted because of its campaigns on issues such as pollution and harmful pesticides.
India accuses the group of “stalling development projects” by protesting against large infrastructure plans.
Since coming to power in May last year, Prime Minister Narendra Modi’s government has cracked down on several non-governmental organisations, leading to critics accusing him of showing undemocratic tendencies.
A month ago, India cancelled the registration of nearly 9,000 foreign-funded groups, saying they did not comply with the country’s tax laws.