The chair of the Labour party has written to her Conservative counterpart calling on him to provide a full list of attendees at a private champagne reception attended by Kwasi Kwarteng just hours after his controversial “mini” Budget.

Jake Berry, Tory chair, has defended the chancellor’s meeting with financiers at the home of a wealthy hedge fund manager. Berry insisted on Sunday that City investors and other donors should be “lauded” by the general public.

Anneliese Dodds, Labour chair, has written to Berry urging him to produce a full list of attendees at the event and whether they paid a fee to be there or pledged donations. She also asked whether civil servants were present and minutes taken, “and if not, then why not” given that sensitive information may have been disclosed.

“Many people are sickened by the image of champagne-quaffing Conservative donors encouraging the chancellor to press ahead with further tax cuts for billionaires, at the same time as many members of the British public are unable to access a mortgage,” she wrote.

But Berry said on Sunday that nothing untoward should be read into the fact that Kwarteng socialised with financial figures soon after the tax cut announcement, which sent sterling into freefall and prompted a sharp rise in gilt yields.

The Tory chair insisted that no confidential information was discussed during the gathering, where he said Kwarteng consumed soft drinks rather than champagne.

“We often have champagne receptions for donors in the Conservative party and, in fact, these people should be lauded because we don’t have public funding of political parties and these are people who make money and donate to political parties in the same way as they do for the Labour party and the Liberal Democrats,” he told Sky News.

Berry said the event was not dominated by hedge funds but instead was attended by “some of Britain’s leading entrepreneurs”. Pressed on whether some hedge fund managers were at the event, Berry conceded this was the case: “There were, or there was I think one that I know of.”

That would appear to be a reference to Andrew Law, head of hedge fund Caxton Associates and a Tory donor, who hosted the private event.

One of the attendees said: “There were 20 or 30 people. It was a briefing by the chancellor after the budget so everything he said was in the public domain, nothing new. It was not a celebration, it was a post-Budget briefing to the people who are likely to be investing in the UK.”

According to The Sunday Times, the guest list included stockbroker Howard Shore, banker Sir Henry Angest, financier Lord Leigh of Hurley and William Salomon of Hansa Capital, along with other figures from industries including hospitality, healthcare and property.

Kwarteng used to work at Odey Asset Management, a hedge fund whose founder Crispin Odey has shorted sterling in recent weeks.