Over 1,600 scientists have signed a letter condemning the Trump administration's plans to roll back Obama-era regulations that redefined and broadened the definition of gender beyond male and female.

The letter  accuses the US government of relying on 'pseudoscience' to justify reversing changes to Title IX gender discrimination law brought in under the Obama administration. 

The Trump administration wants to re-install the traditional definition of gender as being determined by biology via a person's genitalia at birth.

However, the group of scientists claim that the proposals are 'in no way "grounded in science" as the administration claims'.

The government's plans were reportedly detailed in a draft memo by the Department of Health and Human Services that was leaked to the New York Times last week. Despite the report and subsequent backlash in the transgender community, the US government has not yet made any official announcement or comment.

The letter, whose signatories include nine Nobel laureates, states: 'This proposal is fundamentally inconsistent not only with science, but also with ethical practices, human rights, and basic dignity.'

They go on to claim: 'The relationship between sex chromosomes, genitalia, and gender identity is complex, and not fully understood.

'Though scientists are just beginning to understand the biological basis of gender identity, it is clear that many factors, known and unknown, mediate the complex links between identity, genes, and anatomy.'

Liberal activists are also protesting the changes, accusing the Trump administration of trying to 'erase' the transgender community.

Apple, Google, Microsoft, Amazon, Facebook and more than 50 other companies issued a joint statement  this week voicing their opposition to 'any administrative and legislative efforts to erase transgender protections through reinterpretation of existing laws and regulations'. 

However, many Christian groups are among those voicing support for Trump's proposals to bring back the original definition of gender.

The James Dobson Family Institute said it was 'good for America' and that the faith community should 'be encouraged'.

'This is in keeping with the traditional definition of gender the Christian community has always held, and that we as a nation have maintained with uniformity until only recently,' it said in a statement.

'In fact, by taking this courageous and common sense action, the Department of Health and Human Services is simply going back to pre-Obama era regulations and policies.'

It continued: 'We urge Congress to follow the president's lead by providing a legal definition of sex in federal law so that the Title IX legislation is abundantly and legally certain in all instances.

'This is vital not only for the HHS, which must deal with these regulations frequently, but also for all government, including the courts, which requires a clear understanding of what Congress meant by the word 'sex' when they originally established Title IX.'

Denny Burk, theology professor at Boyce College, also defended the Trump administration's position on Twitter.

'Actually, this is simply returning things to where they were before President Obama unilaterally changed the meaning of the word 'sex' in federal statutes like Title IX. He never should have done that and had no right to do that,' he wrote.

He added: 'It's not inhumane or discriminatory to recognize the biological difference between male and female, which is what 'sex' refers to in those statutes. This is not radical. What President Obama did was radical and wrong.'