Switzerland continues to block SFr140 million ($109.5 million) said to be related to Italian Premier Silvio Berlusconi's media empire, Mediaset.
The Federal Court in Lausanne turned down two appeals opposing the blocking of the accounts concerned by the Federal Prosecutor's Office.
The money is said to have been used in the fictitious purchase of film rights by the company.
The prosecutor's office froze the accounts in October at the Manno branch of Switzerland's largest bank UBS near Lugano.
This followed requests for assistance from judicial authorities in Milan in the affair surrounding Mediaset slush funds.
Four companies said to have had relations with the Mediaset group and one individual appealed against the Lausanne court's decision.
The case concerned the purchase and sale of rights to television and movies from the United States by the Mediaset group.
According to Italian judicial authorities, these operations allowed illegal funds to be built up abroad.
Milan prosecutor Fabio De Pasquale has put forward a figure of $170 million accumulated between 1988 and 1999.
Represented by lawyers from the southern Swiss canton of Ticino, the appellants pointed out the financial harm caused by the freezing of the accounts and the impossibility to "respect their contractual obligations".
In its decision, the court considered that "the appellants had not shown concretely that the blocking caused immediate and irreparable harm".
It also noted that the judicial aid given to Italy in the affair was fully justified since Italy and Switzerland had signed the 1959 European Convention on Judicial Assistance.
The Italian prime minister is one of 13 suspects accused of fraud and falsification of accounts. Italian authorities have not yet decided if they are to face trial.
Among them are Mediaset chairman Fedele Confalonieri, a Ticinese banker and the head of the Ticino operations of Fininvest, the holding group of the Berlusconi family.
The Federal Prosecutor's Office on October 3 opened its own investigation regarding money laundering in the Mediaset case, which resulted in the blocking of SFr3 million.
swissinfo with agencies
Mediaset is the leading Italian group in the communication and media sector, and one of the world's major players.
The president of Mediaset is Fedele Confalonieri, while Pier Silvio Berlusconi, son of the Italian prime minister, is the group's vice-chairman.
Mediaset is part of the Fininvest holding group, controlled by the Berlusconi family.
Italian judicial authorities suspect Mediaset of acquiring broadcast rights of United States films at an overvalued price to evade tax.
There are 13 suspects in the case, among them the Italian prime minister, Silvio Berlusconi.