LONDON (Reuters) - BT (>> BT Group plc), seeking regulatory approvals for its 12.5 billion-pound deal to acquire UK mobile network operator EE from Orange (>> ORANGE SA) and Deutsche Telekom (>> Deutsche Telekom AG), has asked the British competition authorities to move straight to a full investigation, avoiding a preliminary review.

BT said in a statement on Monday that it had asked the Competition and Markets Authority (CMA) to proceed directly to a Phase 2 investigation, bypassing the Phase 1 process where the CMA first considers whether a deal might be expected to reduce competition.

Combining BT's more than 10 million retail customers and EE's 24.5 million direct mobile subscribers, and BT's 38 percent share of the fixed-line market with EE's one-third share of the mobile market, the deal was always expected to be closely examined by the regulators.

"This (request) is to allow the CMA efficiently to consider any complex issues in depth without delay, and offers a shorter end-to-end review period compared to the CMA's usual processes," BT said.

Responding to BT's request, the CMA said later on Monday that it was considering whether to fast track the case and asked that any comments on the request to be made by interested parties should be submitted by May 26.

BT hopes to have the acquisition completed by the end of March next year.

But broadband providers Sky (>> SKY PLC) and TalkTalk (>> Talktalk Telecom Group PLC) who buy wholesale access to BT's fixed line network have called on industry regulator Ofcom to break up BT, stepping up the attack since the EE acquisition was announced at the end of last year.

Ofcom said in March it would examine a range of issues including whether there was enough competition in a market that has seen rapid change in recent years as fixed and mobile services converge.

($1 = 0.6368 pounds)

(Reporting by Sarah Young; Editing by Greg Mahlich)