Online music streaming service Spotify has apologised for inadvertently serving a malware infected advertisement on its platform.

The apology came after an advertisement, which was displayed on the ad-supported free desktop version of the service, installed a fake malware infested anti-virus program on users' computers. The company said that people running anti-virus software wouldn't have been infected by the malware.

“We quickly removed all third party display ads in order to protect users and ensure Spotify was safe to use. We sincerely apologise to any users affected. We'll continue working hard to ensure this does not happen again and that our users enjoy Spotify securely and in confidence,” the company said.

The virus, which was designed using the Blackhole Exploit Kit tool for hackers, installed fake anti-virus software called Windows Recovery, security company Websense said in a blog post.

The company said that the attack, termed 'Malvertising', usually occurred on large websites and could be viewed from a web browser. In this case, however, the ad was displayed inside the Spotify desktop application.

Security software maker Avast has revealed that, from the total number of Spotify users who saw the the malware infected advertisement, 59 per cent were in Sweden, 40 per cent in the UK and one per cent in other countries.