CARACAS, Venezuela — Stepping up hostilities with the United States, President Nicolás Maduro of Venezuela expelled the top American diplomat and two other embassy officials from the country on Monday, accusing them of supporting plots to sabotage the country’s electrical grid and the economy.

“Get out of Venezuela! Yankee go home!” Mr. Maduro shouted as he announced the expulsions at a military event to commemorate the bicentennial of a battle in Venezuela’s war of independence.

“We have detected a group of officials of the United States Embassy in Caracas, in Venezuela, and we have been tracking them for several months,” Mr. Maduro said during a live television broadcast. “These officials spend their time meeting with the Venezuelan extreme right wing, financing them and encouraging them to take actions to sabotage the electrical system, to sabotage the Venezuelan economy.”

The expulsions were the latest diplomatic swipe at Washington by Mr. Maduro since he took over for the country’s longtime president, Hugo Chávez, who died in March. Late last year, as Mr. Chávez grew increasingly ill, the two nations held informal talks aimed at improving the long-strained relations between them, and there was some optimism on the American side that Mr. Maduro, a former foreign minister sometimes described as pragmatic, would be amenable to a thaw.