Two American journalists freed by North Korea from months of detention were due to return to U.S. soil early on Wednesday accompanied by former President Bill Clinton, who secured their release in a meeting with the hermit state's leader Kim Jong-il.

Laura Ling, 32, and Euna Lee, 36, reporters for an American cable television venture co-founded by Clinton's former vice president, Al Gore, were to arrive with Clinton at an airport near Los Angeles aboard a private jet from North Korea.

U.S. officials said North Korea was not promised any rewards for their release and there was no link to nuclear non-proliferation talks.

Clinton's wife, U.S. Secretary of State Hillary Clinton, told reporters in Nairobi she was happy and relieved. She added that there was no connection between the effort to free the two journalists and the thorny nuclear issue.

We have always considered that a totally separate issue from our efforts to re-engage the North Koreans and have them return to the six-party talks and work for a commitment for the full, verifiable denuclearization of the Korean peninsula, she said.

The future of our relationships with the North Koreans is really up to them. They have a choice, she said.

A U.S. official said the former president talked to North Korea's leadership about the positive things that could flow from freeing the two women, who had been held since March.

The Obama administration official gave no details, but some analysts have speculated that Clinton's visit and discussions with North Korean leader Kim Jong-il could open the way to direct nuclear disarmament talks.

Analysts said Washington faced a tricky task of trying to convince North Korea to give up dreams of becoming a nuclear weapons power without being seen to reward it for repeated military acts or ignoring the demands of others in the region.

President Clinton had made clear that this was a purely private humanitarian mission, the U.S. official told reporters in Washington after Kim granted the journalists a pardon and allowed them to leave with Clinton and fly to Los Angeles.

North Korea had agreed in advance that Bill Clinton's trip would not be linked to the nuclear issue, said the official, speaking on condition of anonymity.

The official said North Korea would face deeper isolation if it continued provocative behavior that has included nuclear and missile tests. Washington would maintain efforts to enforce U.N. sanctions imposed on North Korea over its May 25 nuclear test, the official added.

The two Current TV journalists were arrested for illegally crossing into the North from China and had been reporting on the trafficking of women. They were both sentenced to 12 years hard labor in June.

Television footage showed the two journalists wearing green and red shirts and carrying luggage, greeted by Clinton as they boarded a plane in North Korea. Clinton put his hand over his heart and then gave a final salute to North Korean officials at the airport.

The U.S.-North Korean encounter in Pyongyang marked the highest-level contact between the United States and the reclusive communist state since Bill Clinton was president nearly a decade ago.

(Additional reporting by Steve Gorman in California, Jack Kim in Seoul, Lucy Hornby in Beijing, Chisa Fujioka in Tokyo, Sue Pleming in Nairobi; and Matt Spetalnick and Paul Eckert in Washington, Editing by Dean Yate and Vicki Allen)