AFP - Unidentified hackers have penetrated the Swiss foreign ministry's computer system to seize data, forcing parts of it to be shut down for several days, the ministry revealed Monday.

The "professional virus attack" allowed outsiders to gain access to the computer system to obtain unspecified information, the ministry said in a statement.

It said the extent of the data mining was unknown.

"Unknown perpetrators used special software in this attack to reach the ministry's IT infrastructure and to acquire specific information," the statement said.

Government computer technicians and specialists from software giant Microsoft discovered the "well hidden" software on October 22.

"In concrete terms, foreign ministry staff cannot use the Internet for the time being but can use the internal network," spokesman Georg Farago told the Swiss news agency ATS on Monday.

ATS had reported over the weekend that the Swiss Finance Ministry and Interior Ministry computer systems also suffered problems on Friday, but it was not immediately clear if these incidents were linked.