British Hindus are being targeted by WhatsApp messages urging them to vote against Labour in the general election, accusing the party of being “anti-India” and “anti-Hindu”.

The messages have also included videos by far-right anti-Muslim activists and have raised fears they are attempting to exploit tensions between British Pakistanis and Indians, as well as different religious groups.

One message said: “The Labour party is now the mouth-piece of the Pakistani government … It is anti-India, anti-Hindu and anti-[Indian prime minister Narendra] Modi. So if there are any Indians who are still voting for Labour, or are still members of the Labour party – then respectfully I say, they are traitors to their ancestral land, to their family and friends in India and to their cultural heritage.”

At the top of the message it said: “Pass this to every true Indian.” At the foot of the message was the name Kapil Dudakia. The Guardian contacted Dudakia, a businessman, but he declined to say whether he wrote the message.

In a recent blog on the Hindu Human Rights website, Dudakia wrote that Labour were “a bunch of left-wing nutters indulging in their prejudices”.

Dudakia also spoke at a Diwali event in the House of Commons hosted by the Tory MP Bob Blackman last month, from which Labour MPs were reportedly banned.

An attendee told the Guardian that Dudakia shouted at the audience to vote Hindus and not Muslims and said that the Conservatives were the only party for Hindus. Dudakia said he spoke at the event in a personal capacity. The Conservative party has been contacted for a response.

The attendee who contacted the Guardian said: “I was told numerous times no Labour MPs were invited because they are anti-Hindu. The whole two hours was all about vote Conservative, and nothing to do with the festival of Diwali. It was the most uncomfortable thing I’ve ever been to.”

Videos sent to Hindu voters via WhatsApp include one in which the rightwing broadcaster Katie Hopkins complains “Islam is taking over my country”, as she criticises a demonstration about Kashmir by British Muslims taking part on Diwali. Others messages include videos by Anne Marie Waters, who leads the far-right For Britain party.

Tanmanjeet Singh Dhesi, the Labour MP for Slough, said: “I urge my Hindu and Sikh British compatriots: don’t fall for the divisive tactics of religious hardliners, trying to wedge apart our cohesive community, circulating lies on WhatsApp.”

Details of the messages have emerged after the president of Overseas Friends of BJP UK, Kuldeep Singh Shekhawat, told the Times of India, the group was actively campaigning for the Tories in 48 marginal seats. The BJP is India’s ruling Hindu nationalist party.

He said: “If the entire Indian community in the UK votes Tory, we will see a swing of around 40 seats to the Tories. This will swing the actual election result.”

At party conference in September, Labour enraged the BJP when it passed a motion calling for humanitarian and international observers to enter the disputed region of Kashmir. The motion came after Delhi’s decision in August to revoke the autonomy of Jammu and Kashmir.