Labour has accused Nigel Farage of attempting to dodge scrutiny as the Reform leader continued to face questions over the £5m gift he received from a crypto billionaire shortly before the last general election.

Asked about the gift from Christopher Harborne on Sunday, the party’s deputy leader, Richard Tice, sought to present it as an irrelevance to voters and said it had complied with all the rules.

When questioned about the Guardian’s revelation of the gift, which Farage had not disclosed, Tice insisted it had been a personal gift that did not need to be declared.

“Nigel was not involved in politics at the time. He’s complied with all the laws,” Tice told the BBC’s Sunday with Laura Kuenssberg programme.

“I trust Nigel’s judgement, and he’s complied with the rules, and thank heavens a wonderful person who’s given that gift is utterly determined to keep Nigel safe and secure.”

The Labour party chair, Anna Turley, said there were serious questions still to be answered about the money, which Farage received shortly before announcing he would stand in the 2024 general election.

“Once again, Farage and his MPs clearly believe there’s one rule for them and another for everyone else,” she said. “He didn’t just take the cash and fail to declare it. He announced a crypto tax cut policy that would directly benefit his secret donor.”

Reform UK gained more than 1,400 councillors across England in this week’s local elections, came second in the Welsh parliament elections and joint second with Labour in Scotland. Farage hailed the results a “historic shift in British politics”.

The Electoral Commission is expected to announce in the coming days whether it will launch a formal investigation into Farage’s £5m gift and if it breached electoral law, with the potential to impose a fine.

Tice said voters knew about the gift and had still chosen to endorse the party, which made sweeping gains across the country in Thursday’s elections.

“The reality is, voters have been made aware of this and then said we want more Nigel, we want more Reform leadership, more Reform councils,” he said.

Tice also said claimed “millions of British voters were enormously grateful” for the money.

“Frankly, £5m is probably not enough,” he said. “The dangers to his life grow. It’s absolutely vital we keep Nigel safe. The state wouldn’t provide the funding, and this was a personal gift based around safety and security.”

He also said the media were trying to smear the party by asking questions about the gift. “The problem that we have is an establishment media that is going to try anything all the time to do us down,” he said.

Multimillionaire Tice has faced allegations that he failed to pay almost £100,000 in corporation tax to the benefit of his investment company, which in turn made donations to Reform.

The parliamentary commissioner for standards could consider whether Farage’s £5m gift was a breach of MPs’ code of conduct. If deemed to be, he could have to make a formal apology or be suspended from parliament, which could in turn lead to a recall petition in his Clacton constituency if he were suspended for more than 10 days.

The prime minister, Keir Starmer, told the Observer: “There are so many questions that Nigel Farage has to answer in relation to this, and there is a reason that he’s running away from those questions.

“I think he should be subject to more scrutiny by parliament, by the media, by the public in relation to this.”

Farage has said he did not intend to stand as a prospective MP but reversed his decision in June 2024 within weeks of receiving the personal gift from Harborne, who is based in Thailand.

Parliamentary rules state that for the 12 months before taking up office as an MP, any benefits for political purposes should be declared.

Harborne donated £9m to Reform last year, the largest ever single donation by a living person to a British political party.