WASHINGTON - Several prominent scientists in exoplanet research have decided to boycott a NASA conference after learning Chinese researchers are barred from attending by the space agency, which cited national security as its reason.

The meeting is scheduled to take place at the space agency's Ames Research Center in California this November and will include both U.S. and international teams who work on NASA's exoplanet-hunting Kepler space telescope program.

But Chinese researchers, including those who worked at U.S. universities and other institutions, were denied the opportunity to attend the meeting. NASA officials reportedly said the rejection is in accordance with a law passed first in March 2011 that prohibits government funds from being used to host Chinese nationals at NASA facilities.

Now, NASA is facing a backlash as several big names in exoplanet research, including Debra Fischer, who leads a research group at Yale University, and Geoff Marcy, an astronomy professor at the University of California, Berkeley, who has been tipped to win a Nobel prize for his pioneering work on exoplanets, announced that they will pull out of the meeting in protest.

Fischer told Xinhua that she learned about the legislation when her Chinese postdoctoral fellow, Wang Ji, had his application to the Kepler Science meeting rejected.

"After contacting the scientific organizing committee and confirming the reason for the rejection, I believed that it was not fair that some of our colleagues were barred from the meeting based on their country of origin," Fischer wrote in an email.

"The meeting is about science and planets around stars, not about national defense. There is no classified information -- it is all publicly available data," she said. "I sent notice that my team at Yale University was formally boycotting the meeting. Some of my esteemed colleagues in the community agreed with this position, including Prof Geoff Marcy at UC Berkeley."

Fischer said that many people are waiting to see if an alternative location can be found so that the meeting is open to everyone but the U.S. government closure right now makes discussion difficult. "It is unfortunate that my colleagues who work on the Kepler mission are caught in the middle," she added.

In an interview with British newspaper, The Gardian, Marcy called the ban "completely shameful and unethical". "It is completely unethical for the United States of America to exclude certain countries from pure science research," Marcy said. "It's an ethical breach that is unacceptable. You have to draw the line."

"In good conscience, I cannot attend a meeting that discriminates in this way," Marcy said in an email to the conference organizers. "The meeting is about planets located trillions of miles away, with no national security implications."

Chris Lintott, an astronomer at Oxford University, told the newspaper that he was "shocked and upset" by the way this policy has been applied.

"Science is supposed to be open to all and restricting those who can attend by nationality goes against years of practice, going right back to cold war conferences of Russian and western physicists," Lintott said. "The Kepler team should move their conference somewhere else -- and I hope everyone boycotts until they do."

The Congressional law has raised fears among some NASA-funded scientists that they will have to sever ties with their Chinese collaborators, and no longer take on Chinese students, the report added.