Obama telephones Bill Clinton to say thank you

US President Barack Obama on Wednesday telephoned former President Bill Clinton to thank him for his "extraordinary humanitarian" effort to get two female American journalist released by the North Korean regime.

"Yes, they (Obama and Clinton) talked for a few minutes right before President Obama went out to speak with you all about his reaction to the journalists being released," White House Press Secretary Robert Gibbs told reporters abroad Air Force One travelling with him to Indiana.

"The President thanked him for a great job and knew how much the families appreciated the President's trip and continued service to the country," Gibbs said, adding that Obama and Clinton are expected to meet soon.

"I want to thank President Bill Clinton - I had a chance to talk to him - for the extraordinary humanitarian effort that resulted in the release of the two journalists," Obama told reporters at White House minutes before leaving for Indiana Wednesday morning.

Reiterating that this was a "private humanitarian mission" undertaken by Bill Clinton, Gibbs said: "I know the President is enormously thankful for his service. I think if the President is ever looking for people to help, former Presidents are always a pretty good group to try."