Kai-Uwe Ricke, chief executive of Deutsche Telekom, has ruled out making acquisitions or stepping up investments for its US mobile phone business in spite of the planned merger of rivals Sprint and Nextel.

The merger means T-Mobile USA will have half the US customers of Sprint- Nextel, Verizon Wireless or Cingular, prompting some concern that it will be unable to match its rivals' investment and marketing muscle in the long term.