The Ukrainian authorities have arrested a number of officials on suspicion of corruption in relation to what they called a “large scale” bribery scheme involving military procurement.

The announcement came days after President Volodymyr Zelensky, under intense domestic and international pressure, backtracked on a move to weaken two anticorruption agencies. His actions against the watchdogs prompted major street protests in Ukraine, the first antigovernment demonstrations since Russia’s full-scale invasion began in 2022.

In a statement on Saturday night, Mr. Zelensky thanked the agencies for their work in the military procurement case, making a point to stress the importance of their independent status — only three days after it was restored in a vote by Parliament.

Mr. Zelensky said that the agencies had informed him that they had uncovered a kickbacks scheme. He said that a member of Parliament, the heads of district and city military civil administrations, and several National Guard servicemen were involved. He did not provide further details.

The agencies — the National Anticorruption Bureau of Ukraine and the Specialized Anticorruption Prosecutor’s Office — issued a separate statement saying that four people had been arrested as part of their investigation into “large-scale corruption” in the procurement of drones and electronic jamming equipment.

“The essence of the scheme was to conclude state contracts with supplier companies at deliberately inflated prices — up to 30 percent of the contract amount was returned to the participants in the crime,” the statement added.

Last month, Mr. Zelensky pushed through a law giving his administration control over the two anticorruption bodies, setting off the street demonstrations. The agencies had been investigating top ministers in Mr. Zelensky’s government, and Mr. Zelensky’s move to kneecap them drew accusations of cronyism.

Amid the protests and strong criticism from Ukraine’s European allies, the president made a rare U-turn and presented a new bill to Parliament to restore the bodies’ independence. The law passed on Thursday.

“There can only be zero tolerance for corruption,” Mr. Zelensky said in his statement on Saturday.