GUATEMALA CITY — President Jimmy Morales of Guatemala on Friday shut down a crusading anticorruption commission sponsored by the United Nations that has pressed a number of high-profile investigations, including one pending against the president himself related to campaign financing.

Speaking in front of civilian and military leaders, Mr. Morales said he had informed the United Nations secretary general of his decision to revoke the body’s mandate and “immediately” begin transferring its capacities to Guatemalan institutions.

Minutes before the surprise announcement, army vehicles donated by the United States that Guatemala uses to fight smuggling operations were deployed to the commission’s headquarters in the capital in what critics called an attempt at intimidation.

The decision caps a long history of friction between the president and the International Commission Against Impunity in Guatemala, also known as Cicig for the initials of the commission’s name in Spanish.