New Delhi CNN Business —  

Facebook is taking down hundreds of suspicious accounts linked to the two main parties contesting India’s election.

With the campaign in full swing, the company removed 687 pages and accounts linked to the country’s main opposition party — the Indian National Congress (INC) — for “coordinated inauthentic behavior,” it said in a statement Monday.

“The individuals behind this activity used fake accounts,” said Nathaniel Gleicher, Facebook’s head of cybersecurity policy. “While the people behind this activity attempted to conceal their identities, our review found that it was connected to individuals associated with an INC IT cell,” he added.

Facebook said it had also removed 15 pages, groups and accounts that frequently posted content supporting the Bharatiya Janata Party (BJP) of Prime Minister Narendra Modi and criticized his political opponents including the Indian National Congress.

The company said those profiles were linked to people associated with Silver Touch, an Indian tech firm that has worked on government projects and reportedly developed Modi’s personal mobile app.

Silver Touch and the BJP did not immediately respond to requests for comment.

The purge of fake accounts comes less than two weeks before hundreds of millions of Indians go to the polls to elect their next leader. Facebook (FB) and Twitter (TWTR) have been stepping up efforts to prevent the spread of misinformation and malicious content on their platforms.

The Congress party is led by Rahul Gandhi, the great-grandson of India’s first prime minister. It’s the main opposition to Modi’s BJP. In a tweet from its verified account, Congress said none of its official Facebook pages had been taken down.

“Additionally, all pages run by our verified volunteers are also unaffected,” it added, saying it was waiting for Facebook to provide a full list.

The pages and accounts in question had more than 200,000 followers and spent around $39,000 on advertising between August 2014 and March 2019, Facebook said.

Those posting in support of Modi, meanwhile, had more than 2.6 million followers between Facebook and Instagram and spent around $70,000 on advertising over roughly the same period.

India is the world’s biggest market for Facebook and its mobile messaging platform WhatsApp, which has found itself at the center of India’s fake news problem after viral hoax messages were blamed for more than a dozen lynchings last year.

The problem is expected to get even more pronounced during the election, with political parties working overtime to get their message out and smear opponents — sometimes through false claims.

Facebook and WhatsApp have taken several steps to make sure their platforms are safe, such as working with fact-checkers, using artificial intelligence to ban accounts and labeling political advertisements. And WhatsApp has warned political parties that their accounts will be blocked if they try to abuse the platform.

Gleicher, Facebook’s cybersecurity head, said Monday that most of the questionable Congress-linked accounts had been “detected and suspended” by the social network’s automated systems.

Facebook also took down 321 other pages and accounts from India that violated its rules against spam, as well as 103 pages, groups and accounts on its own platform and photo-sharing platform Instagram that originated in Pakistan.

“This activity goes against what people expect on Facebook and it violates our policies,” Gleicher said. “We continue to invest in people and resources to improve the technology we use to detect this type of harmful behavior, and we will continue to take action on an ongoing basis to address it.”