Boris Johnson’s decision not to condemn Narendra Modi over the Indian Prime Minister’s policies on Kashmir has become an issue in a British by-election that takes place on Thursday.

The Labour Party is fighting to hold on to the constituency of 80,000 voters at Batley and Spen in West Yorkshire where it has a slim majority of 3,525 and where polling shows the Tories are in the lead.

In an effort to appeal to the constituency’s 8,600 Muslim voters, mostly Pakistani, the Labour party has issued a provocative leaflet showing Prime Minister Johnson shaking hands with Modi, alongside the warning: “Don’t risk a Tory MP who is not on your side.”

It adds: “The risk of voting for anyone but Labour is clear.” The leaflet says of Johnson that he is “a Prime Minister who is silent on human rights abuses in Kashmir”; “accused of whitewashing Islamophobia”; and that he has “compared Muslim women to letterboxes” and said “Islam is the problem”.

There are 16 candidates standing, some representing far-Right groups, but the contest is really between the Labour candidate, Kim Leadbeater, a personal trainer and campaigner who has been attacked among other things for her sexuality, and Ryan Stephenson, chairman of the West Yorkshire Conservatives and a Leeds city councillor.

Leadbeater, 44, is the sister of Jo Cox, a former Labour MP for Batley who died after being shot and stabbed multiple times in the street in a local village on June 16, 2016. Thomas Mair, who held far-Right views, was found guilty of her murder and sentenced to life imprisonment with a whole life order. Tracey Brabin succeeded her as MP but in May 2021 she stood down after being elected the mayor of West Yorkshire, thereby causing the by-election.

In a widely shared video, Leadbeater was confronted by a man who challenged her over the situation in Kashmir and her stance on LGBT+ education in schools. Leadbeater, who asked the man not to shout at her, was pursued and heckled. Critics of the Labour leader, Keir Starmer, have said his leadership will be challenged if the Tories win Batley.

If its politics wasn’t toxic enough, the maverick George Galloway, a one-time Labour MP now standing for the “Workers Party”, has added a further twist. He is trying to attract Muslim votes by raising the issue of Palestinians.

The Labour Party has refused to withdraw its poster.

A spokesman for the party said Labour would “always bring communities together” but then added: “This leaflet makes it clear that a vote for anybody other than Kim (Leadbeater) would lead to a Tory MP who would support a Prime Minister who insults Muslim women and calls it a joke, refuses to deal with Islamophobia in his party and fails to speak out on human rights abuses in Kashmir.”

But this statement has triggered internal warfare in the Labour Party, which lost the 2019 general election partly because of Jeremy Corbyn’s perceived anti-India stance. After succeeding Corbyn as leader, Starmer has tried to steer the party into a more neutral position on Kashmir but this has angered many of Labour’s traditional Pakistani supporters. The latest leaflet has now upset Indians.

Representing Labour Friends of India, its chairman Darren Jones, an MP, slammed the leaflet: “It is unfortunate that the Labour Party used a picture of the Prime Minister of India, the world’s largest democracy and one of the UK’s closest friends, from the G7 in 2019, on its leaflet. We ask the Labour Party to withdraw the leaflet immediately and we will also be writing to the leadership about this.”

Navendu Mishra, who was elected Labour MP for Stockport in 2019, said he had faced racism within the party because of his Indian heritage and Hindu faith and resigned from the shadow government last October: “With regards to leaflets like this, we don’t expect this from Labour.”

He also tweeted: “It saddens me to post this, but racism is alive and well within Labour…. We beat our opponents based on policies, not by dog-whistle racism.”

The veteran Labour MP for Ealing Southall, Virendra Sharma, said: “This divisive leaflet is cheap divide and rule politics not worthy of the Labour Party. Under Keir and Angela’s (Angela Rayner, the shadow chancellor of the Duchy of Lancaster) leadership the party has worked hard to rebuild trust with the Indian community. Leaflets such as this will undo all of this good work and engagement and I have asked for it to be withdrawn.”

Tory Party chairman and MP Amanda Milling commented: “This is nasty and divisive politics. Once again Labour are playing politics rather than focusing on the issues that matter as the country recovers from the pandemic.”

The Sun summed up the situation for its readers: “Tensions are at boiling point in the West Yorkshire town, where many voters are of Pakistani-Muslim descent and massive critics of the Indian regime. Fuming Tory MPs accused local Labour candidate Kim Leadbeater of descending into gutter politics with the material.”

Conservative Friends of India, which is linked to the Conservative Party in the UK, and is a membership organisation which engages with the British Indian community, put out a tweet:

The size of the Indian diaspora is actually 2.5m — and it helped ensure Johnson’s victory in the 2019 general election.

The Yorkshire Post called for calm in a leader comment: “If there is one constituency in the country that deserves a respectfully conducted by-election given its recent tragic history, it is Batley and Spen. The fact that has not happened up to this point is deeply saddening. Calmness and decency must prevail ahead of Thursday’s vote.”