AT&T said it would take a $4 billion charge in case its takeover of T-Mobile USA fails, a tacit recognition of the dwindling chances that the deal will get through US regulators who say it would destroy jobs and curb competition.

The US telecommunications group and T-Mobile owner Deutsche Telekom, said they would continue to pursue anti-trust approval for the $39 billion takeover from the US Department of Justice, but withdrew applications to the industry regulator, for now at least.

'AT&T and Deutsche Telekom are continuing to pursue the sale of Deutsche Telekom's US wireless assets to AT&T,' they said in a statement on Thursday, the Thanksgiving Day holiday in the United States.

The $4 billion sum includes $3 billion in cash and a book value of $1 billion for spectrum access.

Both the DOJ and telecoms watchdog the U.S. Federal Communications Commission oppose the deal, which would reduce the number of national mobile carriers to three.

A senior FCC official said on Thursday afternoon, 'The record clearly shows that - in no uncertain terms - this merger would result in a massive loss of U.S. jobs and investment.'

Withdrawal of the application is subject to approval by the FCC, which has the right to determine whether and how the companies could resubmit an amended application in the future.

In any event, FCC approval would be meaningless if the DOJ blocked the transaction, and AT&T and Deutsche Telekom said they would return to the FCC process if they secured approval from the DOJ.

The collapse of the merger would be a blow to AT&T Chief Executive Randall Stephenson who offered a massive break-up fee to Deutsche Telekom as a sign of confidence the deal, announced in March, would be approved.

Analysts said the merger, badly needed by sub-scale T-Mobile USA - the smallest of the four U.S. mobile operators - looked less likely than ever to succeed.

Espirito Santo analysts said AT&T's decision to take the $4 billion charge this quarter showed that the company's own assessment of the chances of success had fallen.

'It tells us something about timing too - suggesting that AT&T may decide to walk away at the first opportunity (March 20, 2012) rather than waiting for the ultimate September 20, 2012 deadline,' they wrote in a note to clients.

Deutsche Telekom shares finished the day down 0.6 percent at 8.69 euros.

The companies' advisers stand to lose a total of $150 million in fees. T-Mobile's advisers Deutsche Bank, Credit Suisse, Morgan Stanley and Citigroup, and AT&T's banks Greenhill & Co, Evercore Partners and JPMorgan Chase were on course to earn between $18 million and $36 million apiece, according to earlier estimates from Thomson Reuters/Freeman Consulting.-Reuters