The "Kosova Hackers Group" told visitors to the parliament website that it had also attacked other official sites on Wednesday, including the Serbian army's.

The site looked normal on Thursday and parliament had no comment on the incident.

Serbia does not recognise the independence of its former province of Kosovo and objects to the use of its symbols at international gatherings.

"Those hackers are using programmes that are freely accessible on the Internet and can be downloaded free of charge," Slobodan Markovic, an advisor in the Serbian telecommunications ministry, told Radio B92.

Markovic said Serbian government sites do not have a unique security system but that each ministry decides how to protect the data.

The Daily Press said several other official Internet sites were also under "Kosovo Hackers" attack on the same day, including the Defence Ministry, Commercial Court and Serbian Business Registers Agency.