David Cameron will be grilled by two separate panels of MPs on Thursday over his intense lobbying efforts for the failed finance firm Greensill Capital.

The former Conservative prime minister faces a series of difficult questions about his relationship with financier Lex Greenhill and his incredible access to ministers and officials after leaving No 10 in 2016.

Mr Cameron has insisted he broke no rules on behalf of the now-collapsed firm – but admitted he should have communicated with the government “through only the most formal of channels” rather than via text and WhatsApp.

The ex-Tory leader will be under intense pressure to explain his persistent attempts to secure access to a government-backed loan scheme for Greensill when he appears before the Treasury Committee at 2.30pm and the Public Accounts Committee at 5pm.

Tory MP Mel Stride, chair of the Treasury Committee, said he wanted to make sure all the lobbying done in relation to the loan scheme was handled “appropriately”.

Labour MP Meg Hillier, the chair of the Public Accounts Committee who has spoken out on the dangers of “government by WhatsApp”, wants to know more about some of Mr Cameron’s other lobbying work.

The remarkable scale of Mr Cameron’s lobbying efforts during the Covid crisis was revealed earlier this week with the publication of text messages sent to chancellor Rishi Sunak and Cabinet Office minister Michael Gove, among others.

Mr Cameron and his staff sent ministers and officials around 73 emails, texts and WhatsApp messages relating to the now-collapsed firm in less than four months.

They showed Mr Cameron sought to gain access for Greensill to the Bank of England’s coronavirus loan scheme – claiming it was “nuts” and “bonkers” for the firm to be denied the Covid Corporate Financing Facility (CCFF) loans.

The government has been desperate to distance itself from Mr Cameron’s activities, pointing to the fact his attempts were ultimately unsuccessful. On Wednesday the cabinet minister George Eustice insisted his colleagues did not do Mr Cameron “any special favours”.

MPs on the select committee may wish to establish when exactly the former Tory leader first met Mr Greensill, why he brought him in as a government advisor in 2011, while still at Downing Street, and how close the pair became in the years after Mr Cameron left No 10.

MPs on the Public Accounts Committee may also wish to ask about Mr Cameron’s discussions with health secretary Matt Hancock after it was revealed the pair went for a “private drink” in 2019 to discuss a Greensill-run payment scheme for NHS staff.

MPs on both committees may also want to know about Mr Cameron’s share options in Greensill, and how much he stood to make from the firm before its collapse.

The former PM was said to have told friends that he was in line to earn $60m (£43m) from the listing of the company he joined in 2018, The Times reported in March.

Mr Greensill confirmed to the Treasury Committee on Tuesday that Mr Cameron received share options and regularly attended board meetings. But the financier said would not describe the former PM as a “friend”.

Mr Cameron could also face questions about the collapse of Greensill in March. The Financial Conduct Authority (FCA) is formally investigating the company, having received allegations relating to the firm’s collapse that were “potentially criminal in nature”.

In a letter to the Treasury Committee, Mr Cameron said the “first time I became concerned that the company might be in serious financial difficulty was in December 2020” following a call from Mr Greensill.

“Up until that point, I firmly believed that Greensill was in good financial health,” the former Tory leader added.