The federal authorities have blocked the bank accounts of four officials of the former Yugoslav government, led by Slobodan Milosevic. The amount of money frozen has yet to be determined.
The freeze came in response to a request last month by the Yugoslav government, which suspects the four former representatives of having used their positions to enrich themselves, the Justice Ministry in Bern said on Monday.
The accounts are held by three banks in cantons Zurich and Ticino, the Swiss authorities said, but they gave no further details.
Belgrade was given three months to submit further evidence to the Swiss authorities, including a link between any wrongdoing and the money in the accounts.
Accounts blocked in 1999
Switzerland in 1999 had ordered the freeze on any accounts belonging to Milosevic, who was deposed last October, and accounts of four other people accused of war crimes by the International Court of Justice in The Hague.
So far, no suspicious transfer or deposit of funds has been reported to the authorities, the Justice Ministry said. However, a spokesman for the ministry added the freeze was still in place.
There have been unsubstantiated reports that Milosevic or his entourage had sent billions of dollars abroad and that a sizeable sum had been deposited in Swiss banks.
In line with a decision by the European Union, the Swiss authorities last November unblocked assets of the Yugoslav and Serbian governments worth about SFr100 million (then $56 million), because no direct link was found to Milosevic.
The sanctions were originally introduced in 1999 as part of international pressure on Milosevic to step down.
swissinfo with agencies