Cuban government agents have stepped up their verbal harassment of U.S. diplomats in Havana in the past year, shouting epithets at them from moving cars and publishing photos of their vehicles, U.S. government officials say.

“They’ve done this for quite some time, but over the last year or so they seem to have gotten nastier,” said one of the officials. “We have asked them to stop, and they have not.”

The increased badgering appears linked to Cuban President Raúl Castro’s ongoing crackdown on government critics, the officials said. About 4,115 short-term arrests of dissidents were reported in 2011, compared to 1,765 the previous year.

With some U.S. diplomats in Havana specifically assigned to monitor opposition activities, said one official, “when the security forces go after dissidents, (the U.S. diplomats) are usually in the neighborhood and catch the flak too.”

A senior State Department official told El Nuevo Herald that the U.S. government is “concerned about the continued harassment and vilification of our diplomatic mission staff in Havana, who are simply performing their normal diplomatic duties.

“We have reminded the Cuban government on a number of occasions that under the Vienna Conventions, this kind of treatment of diplomatic personnel is not acceptable,” added the official, who asked to remain anonymous because of department policies.

Because Cuba and the United States don’t have normal diplomatic relations, they each maintain an Interests Section in each other’s capital to handle consular affairs and other matters.

Two other U.S. government officials fleshed out some of the details of the incidents, also on the condition of anonymity.

In one case, several Cuban men in a car pulled up next to a U.S. diplomat driving in Havana with one of his children on board, called out his name and shouted several epithets at the “Yanqui” before speeding off, one of the officials said.

A pro-government blogger who uses the name of Yohandry posted a photograph of a U.S. diplomat’s car and a text noting that if a rock “was to fall from the sky” and break a window, news media reports would surely say the car had been “attacked.”

Other government supporters have posted photos of Charles Barclay, the deputy chief of the U.S. diplomatic mission in Havana, meeting with dissidents and of another American diplomat hugging Berta Soler, leader of the Ladies in White, a dissident group.

There is also suspicion that Cuban officials try to rattle the diplomats through surveillance by blatantly visible security agents and by occasionally shutting off the electricity and water services to their homes, one of the officials said.

The Cuban government regularly brands dissidents as “mercenaries” paid by Washington to undermine the communist system, and views anyone who approaches government critics with suspicion.

State Department officials have complained in the past of Cubans vandalizing diplomats’ vehicles, breaking into their homes to leave behind intimidating signs of their presence — feces in at least one case — and trying to poison family pets. But no such cases have been reported in recent months.

The Cuban Interests Section in Washington did not reply to emails seeking comment.