AMSTERDAM (Reuters) - The European Commission needs to take another look at how it approved the merger between Dutch cable companies UPC and Ziggo in 2014, an EU court ordered on Thursday, in a case brought by the companies' rival, the former state telecoms monopoly KPN (>> Royal KPN).

The Commission failed to properly explain the effects of the merger on competition in its October 2014 decision, specifically on the market for pay TV sports channels, the court said.

The merger of Ziggo and UPC, owned by Liberty Global (>> Liberty Global PLC), brought together the two largest cable network operators in the Netherlands.

Liberty Global last year merged the combined entity with Vodafone's (>> Vodafone Group) Dutch subsidiary to create VodafoneZiggo after being vetted by the competition regulators.

VodafoneZiggo said the court's decision would have no effect on its operations.

"We are confident we will still get approval for the merger", spokesman Gradus Vos said. "The court's objections strictly relate to the procedure the Commission followed, not to the reasons for approval."

KPN, however, said it was pleased with the decision.

"It is now up to the European Commission to decide what they will do with it", said spokesman Stefan Simons.

The Commission, which can appeal against the ruling at the European Court of Justice, said it would "carefully analyse" the judgement.

(Reporting by Bart Meijer; Editing by Greg Mahlich)

Stocks treated in this article : Royal KPN, Liberty Global PLC, Vodafone Group