CARACAS (Reuters) - Two Venezuelan firefighters were detained by military officers this week as suspects behind the making of a viral video that mocked unpopular President Nicolas Maduro by likening him to a donkey touring a fire station, two rights groups said on Friday.

Government critics, who say former bus driver and union leader Maduro is to blame for oil-rich Venezuela’s brutal five-year recession, have long nicknamed him “Maburro,” a play on the Spanish word for donkey, “burro.”

The video showed a man using a rope to lead a donkey through a fire station in the Andean state of Merida. A narrator feigns guiding the president on an official visit in a style that seemed to make fun of fawning coverage on state television.

“Good evening comrades, as you can see we are receiving the visit of President Maduro. He is doing an inspection,” the man filming says in the video, as the donkey slowly walks through a dimly lit, spartan fire station.

As the donkey chews on a verdant patch overlooking a valley, the narrator says, “He is checking whether the grass is in a good state or not.”

“He is indicating that the grass is good - that is the only good thing we have here at the station,” the narrator says, alluding to the recession. “Now go to the bathroom, so you can see the conditions. Or the kitchen.”

Members of Venezuela’s military counterintelligence unit DGCIM arrested the two firemen, Carlos Baron and Ricardo Prieto, on Wednesday, according to rights group Espacio Publico. But a human rights observatory that is part of the University of the Andes in Merida said the arrests were on Thursday.

“We know the DGCIM took them away, but we do not know where they are,” Mary Isabel Rodriguez of Espacio Publico said on Friday.

Venezuela’s Information Ministry did not respond to a request for comment. Baron and Prieto could not be reached.

Opposition politicians say Maduro has morphed into a dictator by arresting rivals and cracking down on dissent. Maduro says he is facing an armed uprising backed by his foe the United States.