The Trinamool Congress has written to Facebook CEO Mark Zuckerberg to raise the issue of alleged bias of the social media giant towards the BJP, and claimed that there is enough evidence in the public domain to substantiate this charge.

Party MP Derek O'Brien, who has written the letter to Zuckerberg, also refers to an earlier meeting between the two, where some of these concerns were raised.

Sources in the party said that O'Brien met Zuckerberg in Delhi during October 2015.

"We, the All India Trinamool Congress (AITC), India's second-largest opposition party, have had serious concerns about Facebook's role during the 2014 and 2019 general elections in India," O'Brien wrote in the letter dated August 31, accessed by the PTI.

"With the elections in the Indian state of West Bengal just months away, your company's recent blocking of Facebook pages and accounts in Bengal also points to the link between Facebook and the BJP. There is enough material now in the public domain, including internal memos of senior Facebook management, to substantiate the bias," he wrote.

The Rajya Sabha MP also informed the CEO of Facebook that the matter was raised by the party in Parliament in June last year.

"This was done during the discussion on the Motion of Thanks to the President's Address. We are enclosing the relevant portion (video) of that Parliamentary speech, along with this letter.

"We were optimistic that the issues and concerns we raised on the floor of Parliament 14 months ago would empower other political parties and the media to also address this substantive issue, he said in the letter.

"The recent series of articles that appeared in the BBC, Wall Street Journal, Reuters, Time Magazine and others, vindicate our stand,” he added.

O'Brien also states that he had met Zuckerberg a few years ago and expressed his concerns over some of these issues and urged him "in the interest of transparency, to investigate these serious charges against Facebook's senior management in India".

"Please do all it takes to urgently work towards maintaining the integrity of your platform in the Indian electoral process," the letter states.

Earlier, the Congress party had written to Zuckerberg, demanding a probe into the alleged bias and interference of the social media giant's India leadership team in the country's electoral democracy, even as the BJP had taken a swipe at the opposition party, saying any organisation that does not work to its liking is accused of acting under BJP-RSS pressure.

A massive political row broke out after a report by the Wall Street Journal (WSJ) last week alleged that senior Facebook executives had opposed applying hate speech rules to posts by certain BJP leaders.

Last month, a Facebook spokesperson had said, "We prohibit hate speech and content that incites violence and we enforce these policies globally without regard to anyone's political position or party affiliation.

"While we know there is more to do, we're making progress on enforcement and conduct regular audits of our process to ensure fairness and accuracy,” they said.