A row is reportedly growing in the US over attempts by the White House to censor scientific information coming from Nasa.

There are signs of increasing tension within the organisation, and one scientist has claimed that he has been told to stop talking about climate change or face "dire consequences".

Another reported case involves a political appointee attempting to get the theory of creationism onto the Nasa website.

In the latter case George Deutsch, a presidential appointee to the Nasa press office whose previous experience involved working for the Bush/Cheney campaign, sent an email questioning Nasa's website in October, which was leaked to the New York Times.

"The Big Bang is not proven fact; it is opinion," Deutsch wrote. "It is not Nasa's place, nor should it be, to make a declaration such as this about the existence of the universe that discounts intelligent design by a creator."

Now the agency's administrator, Dr Michael D. Griffin, has stepped in to settle the row.

"It is not the job of public affairs officers to alter, filter or adjust engineering or scientific material produced by Nasa's technical staff," Dr Griffin wrote in an email to the agency's 19,000 employees.