The Labour politician Chi Onwurah has insisted that her criticism of Jeremy Corbyn for the way he treated her and another non-white MP was not an “accusation of racism”.

Onwurah, shadow minister for culture and the digital economy, wrote that it was “statistically interesting to say the least” that Labour’s leader had made life difficult for two of the very few minority ethnic female MPs, and he might have faced an industrial tribunal in another sector.

Onwurah said she had been accused of “playing the race card, of reaching a new low” with her complaint about how the leader had behaved with regard to herself and the MP Thangam Debbonaire.

Writing in the Guardian, she said she was accused of colluding with the mainstream media, of choosing the wrong time to speak out and of letting ethnic minorities down. However, she defended her right to speak out about her experience.

“I understand that outrage, in part. The accusation of racism is very serious and it should be: racism remains one of the great evils of our time and the fear of being accused of racism is justified,” she wrote. But she said she was also furious about the reaction because racial inequality was getting worse, not better, and dealing with it meant more than tackling just overt racism.

“When I walk into parliament every day the paintings and images that follow me around are almost exclusively those of white men. Only 6% of MPs are black or minority ethnic. Unemployment rates among ethnic minorities (13%) are twice as high as those for white people. Black workers with degrees earn 23% less on average than white workers with equivalent qualifications. How do we think that happens?” she said.

Onwurah argued that her article about Corbyn was challenging a claim suggesting he was the “only anti-racist in the Westminster village” and showed how he had acted in a way that had stopped two non-white women doing their jobs effectively.

She suggested she did not want the reaction she had had to stop people speaking out about the issue. “What the many battles of the 80s and 90s within the Labour movement taught me is that now is always the best time to raise issues of representation,” she said. “And conflating issues of representation with accusations of racism is one of the ways in which minority voices are silenced. Who wants to be portrayed as the uppity black victim crying wolf to distract from their own shortcomings? Who wants to deal with the resulting outrage when the issue of such a horrible crime as racism is raised?”

Onwurah said she wanted to write after research, revealed in the Guardian, showed that non-white candidates suffered an “electoral penalty” in constituencies with large white populations.

She said that study had reminded her of an exchange with a party member in her Newcastle constituency when she was running to become the candidate for the 2010 elections. The person told Onwurah: “I’d like to vote for you but I don’t know if Newcastle is ready for a black MP. I don’t want us to lose the seat because the BNP exploit the fact we have a black candidate.”

At the time Onwurah said that she was confident that people would just judge her on her achievements and see her as a “local Labour Geordie lass”. She added: “I did not say that the question was like a punch in the gut because I did not want to appear to accuse someone of racism. I would now. Unless we can learn how to have these kinds of conversations with each other across race and gender lines, on the left as well as throughout society, we are doomed to become more, not less, divided.”