Leading Portuguese bank Banco Espirito Santo (BES) was in turmoil on Friday after press reports said its chief executive was about to leave the company and trading in its shares was suspended.
Stock market authorities told the company to clarify the status of its chief executive Ricardo Salgado, 69, who has headed the company for 23 years.
His family, the Espirito Santos, lost their controlling stake in Portugal's largest listed lender after it raised 1.04 billion euros ($1.4 billion) of capital last week.
The bank is also the target of controversy over allegations that its main holding company, Espirito Santo International, had concealed losses.
Press reports allege that the holding company had not revealed a loss of 180 million euros in 2008 when the financial crisis preceding the debt crisis began.
This hole in the accounts then grew to 1.3 billion euros in 2013, it is alleged.
The holding company is being investigated by judicial authorities in Luxembourg, where it is based.
The Portuguese central bank, which has ordered an audit of Espirito Santo International, is believed to have taken discreet action to prevent problems in the company damaging the country's banking system during the upheaval of the financial crisis.
Salgado has acknowledged that the group made mistakes at the level of management in the holding company.
The former accountant for the holding company, Francisco Machado da Cruz, has accused Salgado of being aware of the attempt to cover up the loss by means of revaluing assets.
The bank is Portugal's biggest by capitalisation but has suffered in the debt crisis and is one of four Portuguese banks being scrutinised by the European Central Bank as part of a health check of eurozone lenders.
- Internal power battle -
For the first quarter of this year, the bank reported a net loss of 89.2 million euros, worse than a loss of 62.0 million a year earlier, because of an increase in provisions for bad debts.
For the whole of last year it made a net loss of 517.6 million euros, down from a profit of 96.1 million euros in 2012.
BES, which is active in Portuguese-speaking Africa, Brazil and in Spain, says it intends to use the new capital to strengthen its position as the Portuguese economy recovers.
Salgado also faces an internal challenge over the top job. His cousin, Jose Maria Ricciardi, 59, is making another bid to take over after an unsuccessful attempt in November, but appears unlikely to succeed.
The central bank wants to restrict members of the family within a consultative body and to put the management in the hands of independent professional bankers, press reports said on Friday.
BES is alone among leading Portuguese banks to have refused state help during the crisis, as the family was determined to situation similar to when it was nationalised in 1975 after the overthrow of dictatorship.