By Newley Purnell and Rajesh Roy

Indian lawmakers want to question Facebook Inc. about extremist posts on its platform.

Opposition members of Parliament are acting following an article Friday in The Wall Street Journal that detailed what current and former Facebook employees said was a pattern of favoritism toward the ruling Bharatiya Janata Party and Hindu hard-liners.

Shashi Tharoor, a member of the opposition Congress party who heads Parliament's information-technology committee, wrote on Twitter Sunday that the committee would seek input from Facebook on "safeguarding citizens' rights" and preventing misuse of social-media platforms. It wants to ask the company about reports of favoritism and what it plans to do about hate speech, he wrote.

In a letter to Facebook Chief Executive Mark Zuckerberg Tuesday, Congress party General Secretary K.C. Venugopal said the party has demanded a parliamentary probe and called on Facebook to investigate its India operation, to make transparent "all instances of hate speech" on the platform in recent years, and to consider changing the India operation's management team.

Separately, Aam Aadmi Party spokesman Raghav Chadha, who chairs the peace and harmony committee of the Delhi Legislative Assembly, said in a television interview Monday the committee would summon Facebook's senior management.

Facebook's implementation of its "very comprehensive and detailed rules" on "hateful content that breeds communal disharmony" falls within its jurisdiction, Mr. Chadha said. The committee was established earlier this year following some of the worst communal violence in decades in India's capital city of Delhi.

"We will summon all relevant executives of Facebook, be it in India or global," Mr. Chadha told The Wall Street Journal on Tuesday.

Following the article's publication, Congress party leader Rahul Gandhi said on Twitter that the ruling BJP and a separate Hindu nationalist group "control" Facebook and its WhatsApp messaging service in India.

A Facebook spokeswoman didn't immediately respond to a request for comment.

A BJP spokesman pointed to recent statements from Amit Malviya, the party's national head for information and technology. "It is ludicrous to suggest that Facebook is amenable to the BJP and the wider conservative ecosystem," Mr. Malviya wrote in an Indian newspaper Monday. "If anything, the reverse is true."

The Internet Freedom Foundation, an Indian digital-rights advocate, said Monday that it had written to Parliament's information-technology committee asking it to take such "urgent steps" as summoning Facebook's top global executives, holding hearings and ordering "an international human-rights audit leading to reparations for victims" of hate speech.

The Wall Street Journal reported that Facebook staff charged with policing the platform for dangerous content concluded BJP politician T. Raja Singh had violated the company's hate-speech rules and should be permanently banned from its platforms globally, according to current and former employees. But Facebook's top public-policy executive in India, Ankhi Das, opposed applying the rules to Mr. Singh and at least three other Hindu-nationalist individuals and groups flagged internally for promoting or participating in violence, the current and former employees said.

Ms. Das didn't immediately respond to a request for comment.

India is a key market for the company, home to more Facebook and WhatsApp users than any other country. In April, Facebook said it would spend $5.7 billion on a new tie-up with an Indian telecom operator to expand operations in the country--its biggest foreign investment.

Write to Newley Purnell at newley.purnell@wsj.com and Rajesh Roy at rajesh.roy@wsj.com