U.K. regulator the Financial Services Authority will be getting far more involved in the recruitment decisions made by the firms it regulates, according to a letter it has sent to the CEOs of some 5,000 companies.

Firms that want to appoint someone to a “significant influence function” already have to seek approval from the regulator. But it has now warned that job candidates face a much tougher approval process to determine whether they are fit and proper.