Embattled Labour leader Jeremy Corbyn will launch his campaign to retain his top job in the party this morning (21 July) with a vow to fight workplace discrimination. The left-winger faces a leadership challenge from former shadow cabinet minister Owen Smith, who became the so-called 'unity candidate' after Angela Eagle dropped out of the race.

Corbyn, who attracted almost 60% of the vote in Labour's 2015 leadership election, faced criticism for his performance during the EU referendum and a vast majority of Labour MPs backed a motion of 'no confidence' against him. But the veteran parliamentarian has vowed to stay on, arguing that he would "betray" his supporters if he resigned.

The 67-year-old, who enjoys the support of major Labour-supporting unions such as Unite and Unison, will rally his supporters in London today. Corbyn is expected to highlight five ills – inequality, neglect, insecurity, prejudice and discrimination – in his speech.

"In my campaign I want to confront all five of those ills head on setting out, not only how Labour will campaign against these injustices in opposition but also spelling out some of the measures the next Labour government will take to overcome them and move decisively towards a society in which opportunity and prosperity is truly shared in which no individual is held back and no community left behind," he will say.

Corbyn will add: "Last year Britain was ranked eighteenth in the world for its gender pay gap below Nicaragua, Namibia and New Zealand. We can and must do far better.

"So Labour is calling time on the waiting game and I am making the commitment today that the next Labour government will require all employers with more than 21 staff to publish equality pay audits detailing pay, grade and hours of every job alongside data on recognised equality characteristics.

"Because it is not only women who face workplace discrimination, but disabled workers the youngest and oldest workers black and ethnic minority workers."

The comments will come after Labour reportedly said more than 180,000 people have paid £25 ($33) each to become registered supporters and have a say in the contest, according to Sky News.

Labour's National Executive Committee (NEC) has decided that any eligible Labour member who joined the party on or before 12 January 2016 will be entitled to a vote, ruling out those who joined Labour after the EU referendum. The winner of the contest will be announced in Liverpool on 24 September.