Swiss bankers have pledged to do more to combat money laundering at a seminar in the Swiss capital, Bern.
But Switzerland's largest bank, UBS, said the country could not shoulder all the responsibility for tracking illegal funds.
"There turned out to be very little of [Joseph] Mobutu's money in Switzerland after his death," said Hanspeter Bauer, head of compliance at UBS.
"But nobody investigated neighbouring countries, where he had residences and who were the former colonial powers of his country."
Mobutu, the former ruler of then Zaire - now the Democratic Republic of Congo - is suspected of having laundered billions of dollars of his country's money.
After his death, only about SFr6 million of his funds were found and blocked in Swiss bank accounts.
Switzerland, with its tradition of client confidentiality, has long suffered from a reputation for being a safe haven for dirty money.
But Urs Roth, chief executive of the Swiss Bankers Association (SBA), said Switzerland was taking more than its fair share of the blame for the existence of dirty money in Europe, despite having some of the toughest anti-money laundering rules in the world.
Both Roth and Bauer were speaking at a seminar of banking professionals organised by the SBA.
"We cannot have a situation where people claim that in Switzerland, control weaknesses supposedly keep occurring," Roth said.
"Where Switzerland has excessive regulation compared with the foreign competition, nothing is done about it. In the long run this may produce a widening gap that could be very damaging for our banks and therefore our economy," he added.
Bauer said domestic controls on money laundering were working.
"When you are heading in the right direction and you are convinced you are doing the right thing, then you should do it and not always look at the competition," Bauer said during an address at the seminar.
"Switzerland has proved that it can have stronger rules and still be a leader."
Measures in place
Bauer also said UBS had already introduced stringent rules on opening bank accounts for people suspected of trying to launder money.
He said UBS had drawn up a list of 400,000 foreign government members, heads of state and other officials who are classed as "politically exposed".
"Whenever a minister from another country wants to open an account with us, we check whether he is on our list," Bauer said.
"If they are, we apply a special procedure," he added.
The "special procedure" includes an enquiry into the origin of the person's funds and surveillance of their transactions.
swissinfo with agencies