Britain’s Chancellor Rishi Sunak has been forced to publish text messages sent to former UK prime minister David Cameron relating to the disgraced Australian businessman Lex Greensill.

Greensill Capital’s collapse has embroiled some of the British Conservative party’s biggest identities after it was revealed Mr Cameron was advising the company and used his connections to personally message the Chancellor of the Exchequer seeking help for the firm.

Mr Cameron’s messages have not been published and the former prime minister has refused to respond to media queries for weeks.

Mr Sunak’s correspondence, published under freedom of information early on Friday morning AEST, shows that he rebuffed Mr Cameron.

The first message sent on April 3, 2020 read: “Hi David, thanks for your message. I am stuck back to back on calls but will try you later this evening and if gets too late, first thing tomorrow. Best, Rishi”.

In the second reply sent 20 days later, Mr Sunak said: “Hi David, apologies for the delay. I think the proposals in the end did require a change to the Market Notice but I have pushed the team to explore an alternative with the Bank that might work.

“No guarantees, but the Bank are currently looking at it and Charles should be in touch. Best, Rishi.”

“Charles” refers to Charles Roxburgh, the UK Treasury’s second most senior bureaucrat.

The texts reveal that Mr Sunak did explore ways British taxpayers could financially support Greensill Capital, although this was ultimately rejected.