WASHINGTON, DC, USA (AP) — Republicans briefly brought House Democrats’ impeachment investigation to a halt yesterday as around two dozen GOP House members stormed into a closed-door deposition with a Defence Department official.

Democrats said the move compromised national security as some of them brought electronic devices into a secure room.

The GOP manoeuvre delayed a deposition with Laura Cooper, a senior Defence Department official who oversees Ukraine policy, until mid-afternoon. The interview began roughly five hours behind schedule, after a security check by Capitol officials.

As a series of diplomats have been interviewed in the probe, several of them detailing President Donald Trump’s efforts to persuade Ukraine to investigate a political rival, many Republicans have been silent on the president’s behaviour. But they have been outspoken about their disdain for Democrats and the impeachment process, saying it is unfair even though they have been in the room questioning witnesses and hearing the testimony.

“The members have just had it, and they want to be able to see and represent their constituents and find out what’s going on,” said Ohio Rep Jim Jordan, the top Republican on the House Oversight and Reform panel. That committee is one of three leading the investigation, and its members are allowed into the closed-door hearings.

Democrats deny that Republicans are being treated unfairly, noting they have had equal time to question witnesses and full access to the meetings. But they, said the lawmakers — several of whom do not sit on one of the three committees — compromised security at the closed-door deposition. The interviews are being held in what is called a Sensitive Compartmented Information Facility, or SCIF, which is a secure room where members can hear classified information.

Several lawmakers leaving the facility said that some of the Republicans brought their cellphones, even though electronics are not allowed. All members of Congress are familiar with the protocol of the SCIF, since they are often invited to classified briefings, and there are several such rooms around the Capitol.

Lawmakers described a chaotic scene. Rep Debbie Wasserman Schultz, D-Fla, said she had just walked into the room when the Republican lawmakers blew past Capitol police officers and Democratic staffers. The staff member who was checking identification at the entrance was “basically overcome” by the Republicans, she said.

“Literally some of them were just screaming about the president and what we’re doing to him and that we have nothing and just all things that were supportive of the president,” Wasserman Schultz said.

Senator Lindsey Graham, R-SC, criticised his Republican colleagues for the tactic, calling them “nuts” to make a “run on the SCIF”.

“That’s not the way to do it,” he said.

The Republicans decried that the deposition was happening behind closed doors and said Americans should be able to read the transcripts of any interviews being conducted as part of impeachment.

Rep Steve Scalise, the No 2 House Republican, said Democrats are running a “Soviet-style process” that should “not be allowed in the United States of America”.

“We’re not going to be bullied,” he said.

Democrats have promised to release the transcripts when it will not affect their investigation, and House Intelligence Committee Chairman Adam Schiff has pushed back on the criticism of the depositions.

Schiff said in a letter to colleagues last week that “the majority and minority have been provided equal staff representation and time to question witnesses, who have stayed until the majority and the minority have asked all of their questions — often late into the evening.”

Several Republicans appeared to be tweeting from the secure room. North Carolina Rep Mark Walker tweeted: “UPDATE: We are in the SCIF and every GOP Member is quietly listening.”