Indian social media users have launched an online campaign against Prime Minister Narendra Modi after it emerged that he is following via his Twitter account users who appeared to celebrate and justify the recent murder of a prominent journalist.

Gauri Lankesh, editor of the weekly Gauri Lankesh Patrike publication, was shot dead by unidentified attackers outside her house in Bangalore on Tuesday. Her death sparked shock and outrage across the country, with journalists, politicians and activists sharply denouncing the murder.

Modi has yet to condemn Lankesh's death.

When news reports surfaced that many of the trolls were followed by leaders of the ruling Bharatiya Janata Party (BJP), including several claiming Modi as their follower, many Indians decided to block the prime minister.

#BlockNarendraModi was the top trend in the country on Wednesday night through to Thursday, with users demanding that Modi un-follow the handles and apologise.

One of the tweets in question was sent by user Ashish Mishra, who wrote in response to a news story about Lankesh's death: jaisi karni vaisi bharni (you reap what you sow).

Another Twitter account followed by Modi, Nikhil Dadhich, equated Gauri, an outspoken critic of right-wing groups, to a "bitch". His tweet, written in the Hindi language, was apparently deleted later. Its closest translation read as: "It took a bitch to die a dog's death, for all pups to howl in the same tune".

Many Indians registered their anger by blocking Modi, who is one of the most popular world leaders on Twitter with 33.8 million followers.

An absentee PM who cant care about d country that voted him to power & follows venomous people on Twitter. #BlockNarendraModi is a good idea pic.twitter.com/MAjXNL1lbB — Akshay Bajaj (@villagerurbaine) September 6, 2017

I've never followed him or his ideology. And I'm ashamed he leads my nation, not my leader. #BlockNarendraModi , block filth. — Richa Bhardwaj (@Riczb) September 6, 2017

Narendra Modi became First Prime Minster of India who was blocked on @Twitter by the Citizens for following abusive troll #BlockNarendraModi pic.twitter.com/CkBYKWToUA — Invincible (@i_me_my5elf) September 7, 2017

Thought about it a lot. Finally took the decision to #BlockNarendraModi as he follows too many handles that propagate violence and abuse! — Jay Ambadi (@jay_ambadi) September 7, 2017

**** BREAKING NEWS ****



Just now UNESCO has certified PM as the most blocked PM In the World.



#BlockNarendraModi pic.twitter.com/XMNYyBOIWT — Kamran Shahid (@iKamranShahid) September 7, 2017

Several groups, including the Committee to Protect Journalists (CPJ), have demanded a thorough investigation into the killing, while a Special Investigating Team has been tasked with probing the murder.

The comments against Lankesh drew the attention of Ravi Shankar Prasad, minister of law and justice and of information technology, who condemned the trolls, many of them ruling party supporters, for expressing happiness at the killing of the journalist.

Expressing happiness on the killing of anyone is shameful, regrettable and totally against Indian traditions. Social media is not for that. — Ravi Shankar Prasad (@rsprasad) September 6, 2017

The ruling Bharatiya Janata Party (BJP), however, defended Modi for following trolls.

Amit Malviya, BJP's head of IT Cell, refused to comment on the issue but referred Al Jazeera to a party statement released on Thursday that dubbed the controversy as "mischievous and contorted".

"PM Modi is the only leader who freely engages with people on social media platforms," the statement said.

"The PM following someone is not a character certificate of a person and is not in anyway a guarantee of how a person would conduct himself."

Modi supporters continued to defend him and criticise his opponents for politicising Lankesh's murder.

Congress is trying to #BlockNarendraModi on Twitter - while what it actually needs for its survival is to block Rahul Gandhi from Congress — The Bad Doctor (@DOCTORATLARGE) September 7, 2017

Other social media users disagreed with the Twitter campaign to block the prime minister, arguing in favour of open dialogue.

Don't agree with people who #BlockNarendraModi. Blocking just signals the end of dialogue. Criticise him but don't block. — Meghnad 👨🏫 📖 (@Memeghnad) September 7, 2017

Ankit Lal, who manages the IT division of the AAP party, which governs Delhi, was among the people who advised against blocking Modi - although he added the line "proud to be not followed by PM Modi!" to his Twitter bio.