A Republican congresswoman is facing calls to resign over reports that she helped to spread falsehoods about the Parkland school shooting.

Marjorie Taylor Greene reportedly agreed with a conspiracy theory about the 2018 shooting at Stoneman Douglas High School in Parkland, Florida, in which 17 people were killed.

Facebook screenshots showed a discussion about why a police officer had not rushed into the building, and someone claimed that the mass shooting was a “false flag planned shooting.” Greene replied: “Exactly!”

The social media giant later removed the posts after they were reported to them.

Cameron Kasky, a former Parkland pupil who co-founded the group Never Again MSD, said: “She should resign. She can apologise. I don’t think anybody will accept it.”

The congresswoman was elected in Georgia in November, backed Donald Trump’s claims of election fraud, and has previously expressed support for the QAnon conspiracy theory.

Fred Guttenberg, who’s 14-year-old daughter Jaime died in the Parkland shooting, said: “Your feelings on gun laws are irrelevant to your claim that Parkland never happened. You are a fraud who must resign. Be prepared to meet me directly in person to explain your conspiracy theory, and soon.”

The comments by the politician were first reported by Media Matters for America.

In a statement Ms Greene accused Media Matters for America of being “communists’ and “fake news”.

Meanwhile, US Capitol Police were investigating an incident in which a Republican congressman was found carrying a concealed gun while trying to enter the floor of the House of Representatives.

Andy Harris, a staunch gun-rights advocate, set off a metal detector going through security on his way to the House floor .

Metal detectors were installed outside the chamber to beef up security in the aftermath of the Capitol riots on Jan 6.