Global energy outfit Williams Companies Inc has lodged a $4.9 billion cash bid for Southern Union in an attempt to throw out the $4.2 billion stock deal with Energy Transfer Equity.

The counter bid marks an 18% increase on the $33 per share offer from ETE, with the rival company proposing to buy Southern Union for $39 a share.

Southern Union announced last week it had entered into a definitive merger agreement with ETE which would see the latter company acquire the natural gas player for $7.9