Cisco has revealed that it is challenging Microsoft’s $8.5bn takeover of Internet-calling service Skype at the European Union’s top court, citing concerns that Microsoft would block other video services.

Microsoft completed the deal last October after the European Commission (EC) found it would not hinder effective competition in the European Economic Area (EEA) or any substantial part of it.

The commission found that the parties’ activities mainly overlap for video communications in the area of consumer communications, where Microsoft is active through its Windows Live Messenger.

Cisco’s video and collaboration group senior vice president Marthin De Beer mentioned on the company’s corporate blog that Cisco does not oppose the merger, but believes the European Commission should have placed conditions that would ensure greater standards-based interoperability, to avoid any one company from being able to seek to control the future of video communications.

Networking equipment maker Cisco called for open standards that would allow its users’ to call contacts on Skype or other platforms including Google Talk.

A European Commission spokesperson was reported by the BBC as saying the EC would defend its decision to approve the merger in court.