THE takeover of one of Darlington's biggest employers has been completed.

BT has sealed its £12.5 billion merger with mobile phone firm EE, creating the UK's biggest telecoms company.

The deal was formally completed today, after it was given the green light by the Competition and Markets Authority (CMA) earlier this month. It creates a combination that will have around 35 million mobile, broadband and TV customers.

EE has consistently denied the move would lead to jobs cuts at its Darlington offices where it employs more than 1,500 people. The firm recently announced a multi-million pound investment programme that will see a complete refurbishment of its call centre and billing operations in the town.

The merger deal hands BT 35 per cent of the mobile consumer market and a similar share of the UK's consumer broadband business.

BT will be able to offer bundles of telecoms, TV, broadband and mobile to its customers to compete better with rivals such as Sky and Virgin Media.

Gavin Patterson, BT chief executive, said the new combination would act as "a digital champion for the UK".

But earlier this month, Which? executive director Richard Lloyd said: ''Fewer players in a market is rarely a good thing, but now this deal has been approved both companies must urgently address their abysmal customer service record.

''The regulator will need to keep a very close eye on this to ensure consumers really do benefit from the deal and be prepared to step in if not.''

Last year mobile operator O2 agreed to a sale to Hong Kong conglomerate Hutchison Whampoa, the owner of rival operator Three, for £10.3 billion, further increasing the consolidation across the UK media and telecoms markets.

Aside from this deal, regulator Ofcom is carrying out its first significant review of the telecoms sector for a decade, and is considering options including a split of BT networks business Openreach.

Openreach provides the final mile of network connection into consumers' homes, and is used by rival operators.

Ofcom's Digital Communications Review is expected to be published next month.