Germany, France, Italy, Spain, the Netherlands and Latvia say in a joint statement that the EU needs a "central supervisory unit" to stop the flow of black money in the Union's financial system. The proposal comes after several major European banks in Northern Europe were involved in transactions of black Russian money worth several billion euros.

"Where major financial interests are at stake, there is a risk that national supervision will be affected, directly or indirectly, by institutions that are monitored or by interest groups," the statement states.

Want to see new rules

The demand for reform comes just a few months after the EU agreed to a review of the European Banking Authority to strengthen the Authority's powers to prevent money laundering. The measure has been deemed by some assessors to be inadequate.

The six countries also want to see new rules on money laundering, since the revised provisions introduced a year ago are not considered sufficient.