Danske Bank said today it may be required by authorities to conduct a further investigation into its former Estonian branch, possibly prolonging a money-laundering saga that has dogged Denmark's biggest lender for years.

Danske is under investigation in several countries, including the US, over some €200 billion of suspicious transactions that passed through the bank's tiny Estonian branch between 2007 and 2015.

Late last year, the bank completed a year-long internal investigation into its non-resident portfolio in the now shuttered Estonia branch and handed it over to authorities.

But the lender said today it could be required to "undertake further internal investigation in 2021".

Danske today reported first-quarter profit above expectations on higher fee and trading income, but kept its full-year forecast.

"We saw a positive income development across our business and our cost measures continue to have an effect," newly appointed chief executive Carsten Egeriis said.

Egeriis took the helm this month after former CEO Chris Vogelzang, who was hired to clean up the bank following the Estonia case, quit after being named a suspect in an investigation into alleged money-laundering at his former bank ABN Amro.

"We are making progress with the execution of our 2023 ambitions as planned," Egeriis said.

He was referring to the bank's strategy of cutting costs, increasing profitability and becoming more efficient.

Operating expenses fell 2% in the quarter to 6.3 billion Danish crowns ($1.02 billion), while net profit came in at 3.1 billion crowns, above an average of 2.67 billion forecast by analysts in a Refinitiv poll.