Newt Gingrich, struggling to regain momentum in the Republican presidential primary, is leading the way, promising to get prices down to $2.50 per gallon.

"I've developed a program for American energy so no future president will ever bow to a Saudi king again and so every American can look forward to $2.50 a gallon gasoline," Gingrich said during his self-introduction at Wednesday's CNN debate

WikiLeaks has begun releasing a cache of what it says are 5.5m emails obtained from the servers of Stratfor, a US-based intelligence gathering firm with about 300,000 subscribers.

The whistleblowing site has published 167 emails in its initial release. WikiLeaks says it has partnered with 25 media organisations around the world, including Rolling Stone, McClatchey, the Hindu and Russia Reporter.

Unlike previous WikiLeaks releases, this latest email cache was apparently obtained through a hacking attack on Stratfor by Anonymous in December 2011 rather than through a whistleblower

Anonymous published contact and credit card details from Stratfor and said at the time it had also obtained a large volume of emails for which it would arrange publication.