Estonia's general prosecutor said on Tuesday it had begun a criminal investigation of Danske Bank over allegations that Denmark's largest bank was involved in money laundering through the Baltic country in the past.

Shares in Danske Bank have fallen by almost a quarter this year following allegations its Estonia branch was involved in money laundering between 2007 and 2015.

A Danske Bank spokesman had no immediate comment on Tuesday but said the bank was willing to cooperate with Estonian authorities.

The bank has launched its own investigation into the allegations and will present its findings in September.

Estonia's Prosecutor General Lavly Perling told parliament on Tuesday at an extraordinary meeting to deal with the Danske Bank case that her office had started a criminal investigation into the bank.

The investigation is based on a complaint filed last week by Bill Browder of asset manager Hermitage Capital.

"Now that we have analysed the information provided to us by Mr Browder, we see that there are clear indications of possible money laundering," spokesman for the Prosecutor General's office Kaarel Kallas told Reuters.

Browder's complaint, seen by Reuters, is an application to Estonia's Prosecutor General to conduct an investigation and bring to trial a group of 26 employees of the Estonian branch of Danske Bank.

Kallas said Browder's complaint was not in itself enough to prosecute anyone.

"Now we start collecting additional evidence to get a better understanding of what has happened," he said. Kallas could not disclose the next steps in the investigation.

Under Estonian law a person can face up to five years in jail if found guilty of money laundering and up to ten years if part of a group that has organised money laundering, Kallas said. The maximum fine for a company found guilty of money laundering is €16 million.

Browder, who has been campaigning to expose corruption and money laundering, said it was an important new development as Estonia had been a "key way station" for laundered money.

"Now a real criminal investigation will begin and we will share the information we have and hopefully be able to construct a case where people get prosecuted," Browder told Reuters in a telephone interview.

Browder has also filed a criminal complaint against Danske Bank in Denmark.

Estonia's justice minister, Urmas Reinsalu, and the chairman of the Financial Supervision Authority, Kilvar Kessler, were also summoned to Tuesday's parliament meeting.