Facebook has been accused of being a “morality-free zone” that bullies journalists and threatens academics, as one of its executives appeared in front of MPs.

The Conservative MP Julian Knight told the social network’s chief technical officer, Mike Schroepfer, that the company’s reaction to the Cambridge Analytica scandal suggested a “pattern of behaviour” that included “bullying journalists, threatening academic institutions, and potentially impeding investigations by lawful authorities”.

Addressing Schroepfer, the MP said the social network had tried to evade responsibility for the impact it was having on society: “I put it to you today, sir, that Facebook is a morality-free zone destructive to a fundamental right of privacy.

“You aren’t an innocent party wronged by the likes of Cambridge Analytica. You are the problem. Your company is the problem.”

The Facebook executive said he would “respectfully disagree” with that assessment. “You want us to say we’re responsible, which we have on multiple occasions,” Schroepfer said.

MPs on the Commons’ digital, culture, media and sport select committee have repeatedly requested an audience with Facebook’s chief executive, Mark Zuckerberg, as part of their inquiry into fake news. Instead the company chose to send Schroepfer to answer questions in London.

The executive, who joined Facebook in 2008, also apologised after the social network threatened Guardian Media Group with legal action before last month’s publication of an article in the Observer containing claims about data harvesting at Cambridge Analytica made by the whistleblower Christopher Wylie.

The report detailed how Cambridge Analytica paid a researcher to harvest millions of US voters’ Facebook data using a personality quiz app to try to target them with political advertising. It caused Facebook’s share price to plummet and has prompted investigations around the world.

Schroepfer told MPs that Facebook believed “deeply in the need of journalists to be free to investigate all of these matters”.

To laughter from MPs, he said he understood sending a legal threat prior to publication was “common practice” in the UK to ensure facts in a story were correct.

“It really isn’t,” replied Knight, a former journalist. “I’m going to ask you again: will you apologise for this bullying behaviour?”

Schroepfer said: “I am sorry that journalists feel we are attempting to prevent the truth coming out. I am sorry.”

The Facebook executive also said the site would continue to run political adverts, despite representing a relatively small proportion of their overall business, saying that for politicians “who don’t have an established name” the ability “to reach people via pages and via advertising is a powerful tool of free speech”.

Although the social network has pledged to make political advertising more transparent, Schroepfer admitted that it could be difficult to apply these new rules when non-politicians run adverts on political issues during an election campaign.

He also said Facebook had found no evidence that Cambridge Analytica and its parent company, SCL Group, ran ads on the platform relating to the 2016 EU referendum.

Schroepfer said that while Vote Leave spent millions of pounds during the Brexit campaign on Facebook adverts, he could find no evidence that it used any data obtained through the Cambridge Analytica breach for ad-targeting purposes.

He also told MPs that Facebook would consider using facial recognition technology to stop celebrities such as Martin Lewis being used in scam ads without their permission.

However, Facebook’s chief technology officer plaintively noted that scammers often found ways around his company’s ad filtering system by changing single characters in the text of adverts: “These are people who are financially motivated to evade the systems we have in place,” he said. “They will abbreviate the name: Instead of ‘Martin Lewis’ they will say ‘M Lewis’, or they will misspell the name slightly.”

Asked by Labour MP Jo Stevens about accusations that Facebook is fuelling the persecution of Rohingya Muslims in Myanmar, Schroepfer said the situation in the country is “awful”.

He said Facebook was working to translate some of the company’s tools for combating hate speech into Burmese and other regional dialects, but the company needed more people on the ground in Myanmar. “In regions like this where there is hate and dehumanisation on the platform, the real challenge on the ground is getting more people with local knowledge of all the different dialects of understanding of the cultural sensitives.”