BEIJING (AFP) - Nasa has reversed a decision to ban six Chinese scientists from a space conference, Chinese state media said, after prominent US astronomers vowed to boycott the meeting in a row over academic freedom.

The US space agency had barred them from participating in the meeting on exoplanets - bodies outside the solar system - in California in early November, saying it was legally obliged to do so because of their nationality.

A Nasa committee has now written to the six to change course, China's official Xinhua news agency reported.

"We have since been able to clarify the intent of the referenced legislation and are pleased to inform you that this decision has been reversed and your paperwork is being reviewed for clearance," Xinhua quoted the letter as saying.

"We hope you will be able to join us," it added.

The initial decision to block the six led to an academic uproar and some leading US astronomers, including Yale University's Debra Fischer, announced plans to boycott the conference.

Geoff Marcy, an astronomy professor at the University of California, Berkeley, wrote in an email to the organisers: "The meeting is about planets located trillions of miles away, with no national security implications."

China's foreign ministry also blasted Nasa's denial of the researchers' applications as discriminatory, arguing that politics should have no place at academic meetings.

Nasa administrator Charles Bolden responded earlier this month by pledging to review the committee's decision, which he blamed on "mid-level managers" at the agency's Ames Research Center, which is hosting the event.

Ninety-seven percent of Nasa staff were sent home without pay due to the partial US government shutdown this month after Congress failed to pass a budget in time.