The bosses of three of the UK’s largest gambling companies have infuriated MPs by pulling out of a meeting at which they were due to face questions about their efforts to reduce the dangers of online betting, the Guardian has learned.

The chief executives of William Hill, Flutter Entertainment – previously known as Paddy Power Betfair – and GVC, owner of Ladbrokes, had all confirmed plans to attend a session held in Westminster, only to send their excuses within days of each other.

Carolyn Harris MP, who chairs the all-party parliamentary group (APPG) on gambling harm, which arranged the session, said the withdrawals were “outrageous”.

“These are men who run companies that feed addiction, amass vast profits from the vulnerable and take home huge pay packets, yet they are too afraid to appear before MPs.

“They seem to think they have better things to do than to explain their actions publicly. They are running scared and their actions are cowardly in the extreme.”

The GVC chief executive, Kenny Alexander, was the first to withdraw, according to emails seen by the Guardian, pulling out two days after he was copied into an email to Harris from a compulsive gambler.

The gambler urged MPs to quiz Alexander on claims that Ladbrokes Coral let him squander tens of thousands of pounds, despite him displaying signs of addiction.

There is no suggestion that Alexander’s decision to pull out was influenced by the email and a spokesperson cited “business commitments”, adding that the GVC boss would attend a separate hearing at the House of Lords.

Less than 24 hours after Alexander’s withdrawal, William Hill’s chief executive, Philip Bowcock, also sent his apologies, blaming “commitments around licensing in the UK and some shareholder meetings”.

William Hill will instead send Phil Walker, the group’s managing director of online betting in the UK and Ireland.

“Philip [Bowcock] has met privately with the group and individually with members and we will continue to engage with the group on an ongoing basis,” said a spokesman.

Flutter’s chief executive, Peter Jackson, who had also agreed to attend, cancelled a week after Bowcock and Alexander, due to “unforeseen travel”.

Dan Taylor, chief executive of European operations for the Paddy Power and Betfair brands, will attend in his stead.

The former Conservative party leader Iain Duncan Smith said: “At a time when evidence shows that gambling companies have hounded problem gamblers to get them to carry on gambling, in contravention of their previous assurances, these CEOs now refuse to attend the APPG.

“Their non-attendance speaks volumes about their complicity and they should be condemned for not being prepared to change their ways.”

The Guardian understands that Fred Done, chief executive of Betfred, will not be attending but had not accepted the invitation in the first place because of a prior engagement.

Both SkyBet and Bet365 are expected to send their chief executives to the meeting, which takes place in Westminster on Wednesday.