Israel's supreme court on Tuesday upheld a government decision to expel a senior Human Rights Watch official over his alleged support of a boycott of the country, the ruling said.
Israel has sought to expel Omar Shakir, director for Israel and the Palestinian territories for the New York-based rights group, for more than a year.
It will now be up to the government whether to follow through and deport Shakir, a US citizen, who brands the move a bid by Israel to silence and delegitimise critics of its treatment of the Palestinians.
"If it proceeds, I have 20 days to leave & it'll join ranks of Iran, N Korea & Egypt in blocking access for @hrw official," Shakir tweeted after the decision was announced, referring to Israel.
It would be the first expulsion of its kind under a 2017 law allowing the deportation of foreigners who support boycotting Israel, though there have been cases of people being denied entry under the measure.
The case against him was initially based on alleged statements in support of a boycott he made prior to taking up his post, HRW says.
The government later added new statements it alleges are in support of a boycott.
Human Rights Watch says it has criticised Israel's human rights record but has never advocated a boycott -- and the same is true for Shakir since he joined the organisation.
Israel's ministry of strategic affairs, which probes potential violations of the 2017 law, alleges Shakir's activism, particularly related to the country's occupation of the West Bank, has amounted to calls for a boycott.
The BDS movement -- Boycott, Divestment and Sanctions -- calls for a boycott of Israel over its treatment of the Palestinians.
Israel sees the movement as a strategic threat and accuses it of anti-Semitism -- a claim activists strongly deny.