Israel's decision to expel a U.S. expert on human rights was a "dangerous" move that contravened mandates given to rights advocates working for the United Nations, the UN General Assembly president said Monday.

Richard Falk was detained at Jerusalem's airport on Sunday and then deported back to the United States. Falk's mandate, given by the 192-nation assembly, is to assess the situation in Palestinian territories.

Foreign Minister Tzipi Livni said on Monday that Falk was "unwelcome in Israel."

A Foreign Ministry statement said Falk's visit was uncoordinated and was conducted without the state's authorization and he was therefore turned around.

Israel has long complained about the mandate Falk took over earlier this year, saying it is biased in favor of the Palestinians and prevents the expert from making any comments about human rights abuses committed against Israelis.

He had also personally infuriated Israelis when he compared Israeli actions in the Palestinian territories with those of the Nazis during World War II.

A Foreign Ministry statement explained the decision, saying "in the case of Prof. Falk, beyond the imbalance inherent in his mandate, the bias is further exacerbated by the highly politicized views of the Rapporteur himself, in legitimizing Hamas terrorism and drawing shameful comparisons to the Holocaust. In light of his vehement publications in the past, it is hard to square his appointment with the requirements of the Council's own internal procedures which call for the appointment of mandate holders who are impartial, objective and possess the quality of personal integrity."

Assembly president Miguel d'Escoto Brockmann, who has also criticized Israel in the past, said the Israeli government took a "dangerous decision ... to rebuff UN mandates and UN-appointed mandate holders."

"This again is not conducive to the good climate that the president of the General Assembly is trying to promote," he said in a statement.

Falk, a law professor at New York University, is the UN special rapporteur for human rights in the Palestinian territories.

Miguel d'Escoto said Falk was investigating "human rights violations that affected the protected civilian population of Gaza, the West Bank and East Jerusalem. Most urgently he intended to investigate the rising humanitarian crisis in Gaza Strip resulting from siege of Gaza's 1.5 million population imposed by the occupying power."

Israel earlier this month had lodged a rare protest against Miguel d'Escoto, who criticized the international community for failing to help Palestinians establish an independent state after 60 years on the occasion of the 60th anniversary of the Universal Declaration of Human Rights.

He denied on Monday stories that accused him of preventing the Israeli ambassador to the UN to address the assembly on the 60th anniversary last week, calling those reports "slander" and a "malicious lie."