MEXICO CITY — The Guatemalan government said Monday that it would expel a United Nations-backed anticorruption panel, giving its prosecutors a day to leave the country in the most decisive effort yet by President Jimmy Morales to remove the body that has been investigating him and other top politicians.

At a news conference in Guatemala City, Mr. Morales, accompanied by members of his cabinet and several people accused in panel investigations or their relatives, defended his expulsion order.

“Cicig has put public security and governability at risk,” he said, using the acronym for the panel. “Cicig has repeatedly violated the human rights of Guatemalans and foreigners in Guatemala through selective and partial justice.”

Earlier on Monday, Foreign Minister Sandra Jovel accused the panel of interfering in Guatemala’s internal affairs, and said the government was withdrawing from an agreement with the United Nations that established the panel more than a decade ago.