FRANKFURT (Reuters) - T-Mobile US TMUS.O and Sprint S.N are working to salvage their $74 billion merger and could reach a deal within weeks, the Wall Street Journal reported, citing people familiar with the matter.

Parent companies Deutsche Telekom DTEGn.DE and SoftBank 9984.T reached an impasse last week in their talks as SoftBank directors expressed doubts over giving up control of Sprint, sources told Reuters.

However, the Wall Street Journal said that T-Mobile US has made a revised offer, which Sprint is considering. Terms of the offer were not disclosed.

A Deutsche Telekom representative declined to comment.

Under the previous deal structure, Deutsche Telekom would have controlled the new company, which would have merged the third and fourth-biggest U.S. mobile carriers.

Deutsche Telekom shares were indicated 0.9 percent higher ahead of the Frankfurt market open, compared with a 0.3 percent expected rise for the German blue-chip DAX .GDAXI index.