Israeli interior ministry said on Tuesday it had to deport the representative of Human Rights Watch in Israel and he has to leave within 14 days, accusing him of supporting BDS.
Human Rights Watch, a New York-based rights organisation, said the decision showed that Israel was seeking to suppress criticism of its human rights record, and that it would challenge the decision in court.
Omar Shakir, the group's director in Israel and Palestine, is a US citizen of Iraqi descent. He has denied the accusation against him.
Israel last year initially denied Shakir a work permit, in a move criticised by the United States. It later granted him a one-year work visa.
On Tuesday, Interior Minister Aryeh Deri said he had acted on the recommendation of Public Security and Strategic Affairs Minister Gilad Erdan, whose department said it had gathered data that Shakir had for years supported BDS.
"It is inconceivable that a boycott activist can receive a permit to remain in Israel so that he can act in every possible way against the state. I will use all means to expel such people from the country," Deri's statement said.
HRW said it supported Shakir. "This is not about Shakir, but rather about muzzling Human Rights Watch and shutting down criticism of Israel's rights record," Iain Levine, program director at Human Rights Watch, said in the statement.
"Deporting human rights defenders is a page out of the Russian or Egyptian security services' playbook,” she added.