WASHINGTON, Jan. 19 (CNA) - A dozen members of the US National Guard have been removed from securing President-elect Joe Biden’s inauguration after vetting by the FBI, including two who made extremist statements in posts or texts about the event, Pentagon officials said on Tuesday (Jan 19).

One Guard member was removed from duty after troubling text messages and another had been reported to a tip line, Army General Daniel Hokanson, chief of the National Guard Bureau, told reporters.

The other 10 were for other potential issues that may involve previous criminal behaviour or other activities, but were not directly related to the inaugural event, he said.

"We are, out of an abundance of caution, taking action and immediately removing them from the line of duty at the Capitol and the events taking place," said Pentagon spokesman Jonathan Hoffman.

“Much of the information," Hoffman said, "is unrelated to the events taking place at the Capitol or to the concerns that many people have noted on extremism. These are vetting efforts that identify any questionable behavior in the past or any potential link to questionable behavior, not just related to extremism.”

Their removal from the massive security presence at the nation's capital comes as the FBI worked to vet all of the 25,000 National Guard troops headed to the area for Biden's inauguration on Wednesday.

The FBI is also working to see if any current service members took part in the Jan 6 riot at the US Capitol by supporters of outgoing President Donald Trump.

Last week, the Virginia National Guard said that Jacob Fracker, an off-duty police officer charged in connection with the violent riots at the Capitol, was a corporal in the state's Guard and serves as an infantryman.

Washington has been on edge since the deadly insurrection at the Capitol, which has prompted extraordinary security measures ahead of Biden's inauguration. A fire in a homeless camp roughly a mile from the Capitol complex prompted a lockdown Monday during a rehearsal for the inauguration.

US Secret Service tightened security in and around the Capitol days earlier than usual in preparation, and the city centre is essentially on lockdown with streets blocked, high fencing installed and tens of thousands of troops and law enforcement officers stationed around the area.

Federal law enforcement officials have also been wary of increased surveillance of military and law enforcement checkpoints and other positions after National Guard troops reported people taking pictures and recording them, said the law enforcement officials, who spoke to the Associated Press on condition of anonymity to discuss ongoing security matters.

The Secret Service issued a bulletin over the weekend about what it sees as an “uptick” in National Guard troops posting pictures and details of their operations online.

The Associated Press obtained the “all concerned” message sent to all National Guard troops coming to Washington. Without getting into specific postings, the bulletin read: “No service members should be posting locations, pictures or descriptions online regarding current operations or the sensitive sites they are protecting” and urged them to stop immediately.

Asked about the bulletin, a spokesperson for the Secret Service issued a statement saying it “does not comment on matters of protective intelligence".

Contacted by the AP on Tuesday morning, the National Guard Bureau referred questions to the US Secret Service and said: “Due to operational security, we do not discuss the process nor the outcome of the vetting process for military members supporting the inauguration."

Over the summer, a man was arrested in Los Angeles for impersonating a National Guard member during protests in the city near Los Angeles City Hall.

The man, Gregory Wong, was carrying a sidearm and assault rifle but was taken into custody after actual Guardsmen confronted him when they noticed things out of place on his uniform.