A whistleblower who exposed mass tax fraud involving Swiss banks and US citizens has claimed the CIA is behind the Panama Papers leak.

Bradley Birkenfeld, who served 30 months in prison, but received more than $100 million for US tax authorities revealed the extent of tax fraud at the heart of the Swiss banking industry in 2008.

Commenting on the Panama Papers scandal, he said he did not believe a single whistleblower like himself was behind the disclosure of 11 million documents from law firm Mossack Fonseca and instead suggested the intelligence services were responsible.

Former Swiss banker Bradley Birkenfeld, pictured, who received $100 million from US tax authorities after exposing mass tax fraud has said he does not believe an individual whistleblower is behind the scandal

Birkenfeld said when you look at the countries implicated in the scandal, many of them have difficult relationships with the United States, claiming this suggests CIA involvement in the release

Birkenfeld, pictured, said: 'My feeling is that this is certainly an intelligence agency operation'

In an interview with CNBC from Munich, Birkenfield said: 'The CIA I'm sure is behind this, in my opinion.'

He claimed many of the names included on the list were from countries with difficult relationships with the United States.

He said: 'The very fact that we see all these names surface that are the direct quote-unquote enemies of the United States, Russia, China, Pakistan, Argentina and we don't see one U.S. name. Why is that? Quite frankly, my feeling is that this is certainly an intelligence agency operation.

He added: 'If you've got NSA and CIA spying on foreign governments they can certainly get into a law firm like this, But they selectively bring the information to the public domain that doesn't hurt the U.S. in any shape or form. That's wrong. And there's something seriously sinister here behind this.'

Birkenfeld pleaded guilty in 2008 to conspiring to defraud the United States. Following his revelations, UBS paid $780 million in fines, penalties and restitution.

One of Birkenfeld's legal team said his actions had been responsible for $5billion in taxes being recovered by US authorities.

Meanwhile, organized crime prosecutors in Panama raided the offices of Mossack Fonseca looking for evidence of money laundering and financing terrorism.

A half dozen police officers set up a perimeter around the offices while prosecutors searched inside for documents. Shortly after news reports based on a trove of documents from the firm began emerging more than a week ago, Panama's government had said it would investigate.

The attorney general's office said in a statement that the objective of the raid was 'to obtain documentation linked to the information published in news articles that establish the use of the firm in illicit activities.'

Elias Solano, a lawyer from the Mossack Fonseca law firm, avoids talking with the media outside Mossack Fonseca office in Panama City

Police cars is seen outside the Mossack-Fonseca law firm offices in Panama City during a raid

Police on Tuesday raided the headquarters of the law firm whose leaked Panama Papers revealing how the world's wealthy and powerful used offshore companies to stash assets.s

Mossack Fonseca has denied any wrongdoing, saying it only set up offshore financial accounts and anonymous shell companies for clients and was not involved in how those accounts were used. Co-founder Roman Fonseca told The Associated Press on Tuesday that the firm was preparing a statement.

The search came a day after intellectual property prosecutors visited Mossack Fonseca to follow up on the firm's allegations that a computer hack led to the leak of millions of documents about tax havens.

The firm filed a complaint charging the security breach shortly before the first media reports working with the documents offered details on how politicians, celebrities and companies around the globe were hiding assets in offshore accounts and shell companies.

'Finally the real criminals are being investigated,' Fonseca said in a message to the AP on Monday.

Police officers stand guard at the entrance of the Mossack Fonseca law firm office in Panama City

Police on Tuesday, April 12, raided the headquarters of the Panamanian law firm whose leaked Panama Papers revealed how the world's wealthy and powerful used offshore companies to stash assets

Police with an organized crime unit carried out the raid at Mossack Fonseca "with no incident or interference," prosecutors said in a statement, adding that searches would take place at the firm's Panama City HQ

Fonseca has maintained that the only crime which can be taken from the leak was the computer hack itself. He has said he suspects the hack originated outside Panama, possibly in Europe, but has not given any details.

The law firm is one of the most important in the world for creating overseas front companies.

Panamanian President Juan Carlos Varela has defended the country's financial sector, which is considered of strategic importance for the economy. But Varela has also promised the international community that he is willing to make reforms to make the sector more transparent.

On Tuesday, Varela met with legal, banking and business professional associations. Afterward, he asked France to reconsider its decision to place Panama on a list of uncooperative countries in financial information.

The government announced that Joseph Stiglitz, who won the Nobel Prize in economics in 2001, would be one member of an international panel formed to review Panama's legal and financial practices and recommend improvements.

A man with a jacket that reads "Criminology" enters the Mossack Fonseca law firm office