The UK government's proposal to redefine extremism has raised concerns among some cabinet members who fear it could inadvertently target groups opposed to gay marriage, abortion, or new transgender rights.

The plan aims to combat Islamic and far-right extremism by defining extremism as any ideology that “undermines the rights or freedoms of others.”

The proposed definition comprises three aspects: promoting ideologies based on intolerance, hatred or violence; undermining the UK's democracy; and facilitating such ideologies, including via social media.

Communities Secretary Michael Gove is set to announce the revised definition in the coming days, but critics within the cabinet worry this could impact gender critical feminists and conservative Christian groups.

“It’s going to be incredibly difficult,” a government source said. “You can see how, very quickly, small ‘c’ conservative groups will be hit with this.”

MPs are divided on the issue, with Tory MP Miriam Cates warning that it could lead to a suppression of fundamental freedoms. She likened the broadening of extremism to a “path towards authoritarianism”, and that tackling Islamic extremism should rely on existing laws against violence and terrorism.

She wrote on X, “What does it even mean to ‘undermine British values’ when there is no consensus — and certainly no legal definition — of what those values are? In a free and democratic society with a plurality of opinions and beliefs, it is foolish and dangerous to separate ‘extremism’ from violence and terrorism.

“Some people think that gender critical views are ‘extreme’. I think decriminalising abortion to birth is ‘extreme’. Opposition politicians think the current government is ‘extreme’. Martin Luther King, William Wilberforce and the suffragettes were all viewed as ‘extremists’.

“If ‘extremist’ views are illegal, then the person who defines ‘extremism’ has the power to curtail free speech, freedom of religion, freedom of the press and freedom of association. This is the path to authoritarianism.”

Gove's department is refining the definition so that individuals will have their views on gender, religion or beliefs safeguarded under the Equalities Act.

It is also expected that a new unit will be launched to evaluate individuals and groups that breach the definition – potentially offering a further layer of protection for those who inadvertently fall foul.