Rishi Sunak has rowed back on a £1,000 bet with the broadcaster Piers Morgan on whether deportation flights to Rwanda would take off before the general election, saying he was “not a betting person”.

The prime minister said on Tuesday he had been “taken by surprise” when Morgan said to him during a TalkTV interview: “I’ll bet you £1,000 to a refugee charity [that] you don’t get anybody on those planes before the election. Will you take that bet?”

Sunak shook hands with Morgan on the wager and said he was “working incredibly hard to get the people on the planes”.

The government’s attempt to send people arriving in the UK through irregular means to Rwanda for their claims to be processed has been blocked by the supreme court, which ruled the policy was unlawful in November. Sunak has said he can salvage the scheme.

However, when asked about the “bet” in an interview on BBC Radio 5 Live on Tuesday, Sunak said: “I am not a betting person and I was taken totally by surprise in that interview.

“The point I was trying to get across – I was taken totally by surprise – was actually about the Rwanda policy and about tackling illegal migration, which is something I care deeply about.

“Obviously people have strong views on this and I was just underlining my absolute commitment to this policy, my desire to get it through parliament, up and running because I believe you need to have the deterrent.

“I believe you have got to have a deterrent, you have got to have somewhere you can send people so that if they come here illegally they won’t be able to stay.”

However, soon after Sunak’s claims that he was “not a betting person”, it was pointed out on social media that that he had worked in the past as a hedge fund manager and had boasted about discovering the “dangerous” pleasures of spread betting online around the same time.

​In an interview last year for an episode of the BBC’s Test Match Special podcast, Sunak had recalled that time, saying: “So I was sitting there on one side working, doing my finance job, and on the other screen I was doing next wicket partnership, next wicket for, innings total. I just discovered this thing and it was great.”

Opposition parties criticised Sunak’s decision to agree to the bet with Morgan. The shadow paymaster general, Jonathan Ashworth, said: “Not a lot of people facing rising mortgages, bills and food prices are casually dropping £1,000 bets. It just shows that Rishi Sunak is totally out of touch with working people.”

The Scottish National party reported Sunak to the independent adviser on ministers’ interests, Laurie Magnus, claiming the bet could be a breach of the ministerial code.

Asked if he understood the financial pressures facing ordinary households, given he had made a £1,000 bet on a whim, Sunak said: “When it comes to cost of living, when I first got this job I set out five priorities – the first of them was to halve inflation because I absolutely understood that the cost of living was the most pressing problem most families faced.”

Asked if it shocked him that poor families were reportedly having to water down baby formula, the prime minister replied: “Of course I am sad to hear that people are in that situation.”

He said it was difficult to comment on individual cases that were put to him and he committed to sitting down with the people involved if he was written to.