A pledge by Nigeria’s new central bank governor to take tough action to clean up the financial sector has triggered a sharp sell-off on the Lagos stock market amid fears he may force banks to declare big losses.

In an interview with the Financial Times, published on Monday, Lamdio Sanusi said he would conduct an audit of banks’ exposure to the local capital market as a first step to tackle an overhang of bad debts that have sapped trust in the system.