Dr Spash yesterday lashed out at his former employer, saying it had treated him ''extremely poorly''. He said the organisation had gagged his views on emissions trading schemes.

The spat centres on a paper Dr Spash wrote, The Brave New World of Carbon Trading, which criticised cap and trade schemes, such as that proposed by the Rudd Government.

The CSIRO refused permission for the paper to be published in the journal New Political Economy because it deemed it in breach of the CSIRO charter, which prevents staff from publicly debating the merits of government or opposition policies.

The CSIRO's chief executive, Megan Clark, later agreed to publish the paper, subject to amendments she would negotiate with Dr Spash. But last week - under pressure from Coalition and Greens senators - the Science Minister, Kim Carr, tabled in the Senate an unamended version of the paper, which Dr Spash, 47, had released in his private capacity, in breach of CSIRO policy.

Dr Spash said the CSIRO charter, introduced by the Rudd Government last year, was leading to self-censorship. ''The way the publication policy and the charter are being interpreted will encourage self-censorship,'' he said.

This follows previous allegations of censorship by the CSIRO of its climate scientists, raised by the ABC in 2006. In April this year, four CSIRO scientists were not allowed to give evidence to a Senate inquiry into climate change in a CSIRO capacity.

Dr Clark yesterday rejected claims that Dr Spash had been harassed or his work censored.

''CSIRO staff are actively encouraged to debate publicly the latest science and its implications and to analyse policy options. However under our charter we do not advocate for or against specific government or opposition policies,'' she said.

''The CSIRO charter protects the independence of our science. It also protects CSIRO scientists from being exploited in the political process.

''Since February 2009, we have attempted to work through these issues with Dr Spash in a respectful way. I absolutely do not accept that asking Dr Spash to meet standards which are met by all our other staff could be considered harassment,'' she said.

British-born Dr Spash is going to Europe and plans to stay indefinitely.