US telecoms giant AT&T's bid to buy rival T-Mobile USA could be facing collapse after the US government sued to block the $39bn (£24bn) deal.
AT&T agreed to buy the firm from Deutsche Telekom in March, aiming to create the largest US wireless network.
But the Justice Department says the merger would violate US anti-trust law and has requested a court order to stop it going ahead.
The deal would have given AT&T about 43% of the US mobile phone market.
However, it cannot go ahead without approval from both the Justice Department and the Federal Communications Commission (FCC).
"The combination of AT&T and T-Mobile would result in tens of millions of consumers all across the United States facing higher prices, fewer choices and lower quality products for mobile wireless services," said Deputy Attorney General James Cole. More...