Demanding a high-level judicial probe into it, Yadav said allowing such lethal medicines amounts to a “conspiracy to murder someone” and those responsible should be prosecuted.

"Around 80 crore Indians have been given the Covishield vaccine, which is two doses per person, and the company that made its original formula has said that it causes a risk of heart attack,” Yadav said in a post on X.

“Those who have lost their loved ones due to the side effects of the vaccine or who feared the ill effects of the vaccine, their doubts and fears have now been proven right," the former Uttar Pradesh chief minister said.

Those who play with the lives of the people will not be forgiven, he said.

UK-headquartered pharma giant AstraZeneca has admitted that in "very rare cases", its COVID-19 vaccine, which is known as Vaxzevria in Europe and Covishield in India, can cause a blood clot-related side effect but the causal link is unknown, according to court papers being quoted in the UK media.

In India, the AstraZeneca vaccine was manufactured by the Serum Institute of India.

Attacking the BJP, the SP chief further said, "The ruling party has put the lives of the public at stake by collecting political donations from the vaccine manufacturing company."

“Neither the law, nor the public will ever forgive them. There should be a judicial inquiry at the highest level in this matter," Yadav added.

SP leaders had made similar allegations on Tuesday, saying the BJP took "commission" from the manufacturer of the Covid vaccine, which they said was "forcibly" administered to people.

Uttar Pradesh Congress chief Ajay Rai had also attacked Prime Minister Narendra Modi over the issue. "Is this Modi's guarantee?" he had asked.

SP national general secretary Shivpal Yadav had said, "It has now been exposed that they have taken commission in vaccines too. Low quality vaccines and medicines were given to the people."

Dimple Yadav, wife of SP chief Akhilesh Yadav, said people were "forcibly" administered Covid vaccines in the country.

"A donation of Rs 200-300 crore was taken (by the BJP) and they (company) were given permission to market the vaccine. People were forcibly administered vaccines. No where in the world vaccines were administered forcibly,” Dimple said, adding that corruption in vaccine manufacturing has now come to the fore.

Akhilesh Yadav, while the country was under the impact of COVID-19 pandemic, had said that he would not take the "BJP's vaccine", and that when his government comes to power, everyone would be vaccinated for free.

The Daily Telegraph reported that in a legal document submitted to the High Court in London in February for a group action brought by 51 claimants, AstraZeneca admitted that the vaccine developed with the University of Oxford to protect against COVID-19 may cause Thrombosis with Thrombocytopenia Syndrome (TTS) in "very rare cases".