The U.S. cable operator and Spanish telecoms provider want to better compete with market leader BT with the $38 billion deal combining Virgin Media and O2.
They sought European Commission approval on Sept. 30 while CMA requested to take over the review on Oct. 8 because of the deal's impact in Britain and after Brexit.
The EU competition enforcer, which has a Nov. 19 deadline for its preliminary scrutiny, declined to comment. It has, in the past, preferred to examine telecom cases rather than cede them to national watchdogs to maintain a harmonised policy across the 27-country bloc.
"We remain in constructive dialogue with all relevant stakeholders at the EU and CMA and continue to work to the timeline of completing the deal mid-next year," the companies said in a joint statement.
(Reporting by Foo Yun Chee; editing by Bernadette Baum and Jason Neely)
By Foo Yun Chee