Accountants and lawyers are among at least 30 people asked to hand over information about collapsed mini-bond provider London Capital & Finance, according to The Times.
Before its collapse at the end of January, £237m had been invested in LCF by some 11,500 private investors.
The firm had previously raised flags with the FCA for marketing material the regulator ruled as misleading.
The Times understands that administrators at Smith and Williamson have demanded information from a number of companies linked to the firm, including auditors at EY and PWC, which signed off LCF’s accounts.
Kent-based law firm Buss Murton has also been subject to requests, the paper reports.
Court action could follow under enforcement powers granted to administrators and their lawyers through the Insolvency Act if individuals do not turn over information.
Law firm Mishcon de Reya partner Mike Stubbs says his firm expects “some recipients will not co-operate and will be dragged into court”.
Stubbs adds some 20 further letters will be sent in the coming weeks.
The Times reports bondholders are due to meet this Wednesday in London.
EY and PWC declined to comment to The Times.