Hungary's parliament voted Tuesday to bar nationals from legally changing their gender, defying protests at home and abroad and warnings that transgender citizens will face greater discrimination.

The text of the new law as passed says gender would be defined as "biological sex based on primary sex characteristics and chromosomes".

The law makes it impossible to change a person's sex recorded at birth and therefore also prevents changing one's legally recognised gender. Hungarian LGBT rights organisation Hatter called the move "sad and outrageous" and said it ignored "practical and human rights concerns raised by dozens of civil society organisations and international bodies."

Critics fear nationalist Prime Minister Viktor Orban's government is pushing through parts of its controversial socially conservative agenda while attention is distracted by the coronavirus crisis.

"We will not give up the fight: we ask the president of the republic to send the law for review to the Constitutional Court," Hatter said in a statement sent to AFP, adding that it would explore possible legal challenges to the law, both in Hungary and abroad.

Rights activists say the new law will expose transgender Hungarians to greater discrimination in employment, housing, access to goods and services and official procedures. Earlier this month parliament -- dominated by Orban's Fidesz party -- rejected the ratification of a treaty aimed at combatting violence against women.

The government opposes the Istanbul Convention partly on the grounds that it promotes "destructive gender ideologies".

Since Orban came to power in 2010, his government has pursued several policies it says uphold traditional Hungarian values, including inserting a definition of marriage in the constitution as being between one man and one woman and a 2018 decree which effectively banned universities from teaching gender studies courses.