GUATEMALA CITY (Reuters) - Guatemala’s government, appearing to defy an order by a top court, said on Monday it would not permit the leader of a U.N.-backed anti-corruption body to return to the country, prompting opponents to warn of a constitutional crisis.

FILE PHOTO: Ivan Velasquez, head of the International Commission against Impunity, speaks during an interview with Reuters in Guatemala City, Guatemala September 14, 2017. REUTERS/Luis Echeverria

Guatemala’s Constitutional Court on Sunday ordered the government to lift the ban put in place by President Jimmy Morales last month after he said he would not renew the mandate of the International Commission Against Impunity in Guatemala (CICIG).

Speaking to reporters on Monday, a government minister said CICIG head Ivan Velasquez, an investigator whose work helped bring down and imprison a previous Guatemalan president and has put pressure on Morales, would not be allowed to set foot in the country.

“The Colombian citizen Ivan Velasquez Gomez will not enter national territory,” Interior Minister Enrique Degenhart said.

The government has argued that the court order did not specify Velasquez by name. The foreign minister asked the United Nations on Monday to name an alternative commissioner, giving it 48 hours to do so.

The government’s stance heightened a growing standoff between the president’s loyalists and CICIG supporters, thousands of whom have protested in the streets in recent days.

After Degenhart’s remarks, several activist groups said they had presented a formal complaint to the attorney general’s office against Morales and members of his administration.

“Disobedience of the Constitutional Court demands removal,” Claudia Samayoa, a human rights activist in Guatemala, told a news conference.

Attorney General Consuelo Porras said that if the court deemed the government to be in violation of its ruling, her office would take legal action.

Established in 2007 to investigate criminal groups in Guatemala, CICIG has the authority to conduct independent investigations, act in conjunction with the country’s prosecutors and make public policy recommendations.

The body brought down Morales’ predecessor with a corruption probe and sought to prosecute Morales over illegal financing allegations. He has denied any wrongdoing.