Markwayne Mullin, the Department of Homeland Security secretary, told lawmakers on Wednesday that his agency would be increasing the training requirements for Immigration and Customs Enforcement officers to their previous level starting this summer.

The scope of ICE training became a point of contention as the Trump administration hired thousands of new officers over the past year and apparently cut training requirements as a result of the hiring push. A trove of documents released by Senate Democrats earlier this year showed that training hours had dropped by roughly 40 percent as of February, to approximately 336 hours. As of last July, it had been 584 hours.

On Wednesday, Mr. Mullin said that those training requirements were changing.

“We had to rewrite the curriculum. All training starting July 1st will be back up to the regular standards,” he said to the House Homeland Security Committee.

The issue of training for new ICE officers became a flashpoint as the agency became involved in major operations in cities like Minneapolis. The shootings of two American citizens in that city, one of whom was shot by an ICE agent, further inflamed those conversations.

Then, in February, Ryan Schwank, a former ICE attorney who worked at the training academy, publicly criticized the changes.

“For the last five months, I watched ICE dismantle the training program,” Mr. Schwank said in February, at a forum held in Washington by congressional Democrats. “Cutting 240 hours of vital classes from a 584-hour program — classes that teach the Constitution, our legal system, firearms training, the use of force, lawful arrests, proper detention and the limits of officers’ authority.”

Agency officials pushed back and said that hours had in fact not been slashed. “Our officers receive extensive firearm training, are taught de-escalation tactics, and receive Fourth and Fifth Amendment comprehensive instruction,” the agency said at the time.