The chief of the National Investigation Agency (NIA) said on Sunday that youths in South India were getting more influenced by the Isis ideology than those in other parts of the nation.

At the foundation laying ceremony of NIA's new office in Lucknow, NIA director general Sharad Kumar said the number of radicalised youths in southern states is higher than that of states like Uttar Pradesh and Bihar, The Times of India reported.

The NIA chief said social or economic reasons are not to be blamed for radicalisation of youth by the Islamist extremist group. In view of the increasing number of cases of radicalisation, the Centre has started an anti-radicalisation campaign, Kumar said, according to TOI.

Earlier reports suggest majority of Indian youths who are under the radar of the security forces for their alleged inclination towards the Islamic State are from South India.

In an interview with India Today channel last month, Union Minister of State for Home Affairs Kiren Rijiju said "it is reality" that most of the youngster coming under the influence of Isis' ideologies are from Andhra, Kerala, Telangana, Karnataka and Tamil Nadu.

At least 150 youths who allegedly sympathise with Isis are under the surveillance of the security agencies and most of them are from South India, PTI reported. "Most of them are in regular contact with some ISIS activists through online. Hence, we have kept all them under surveillance of security forces," PTI had quoted an official linked to the investigation as saying.

The intelligence agencies were reported to have identified at least 20 Indians who joined the Isis in Syria and Iraq. While one returned to India, six others died while fighting for the Sunni extremist fighters in the Middle East. The Indian authorities also prevented 30 more Indians from leaving the country to join the terrorist group.

Recently, three youths from Mumbai were suspected to have joined Isis after they went missing from the Malwani suburb. However, one of them was arrested by Maharashtra Anti Terrorism Squad (ATS) in Pune on 22 December.

The ATS arrested 25-year-old Wajid Sheikh, while 23-year-old Ayaz Sultan and 26-year-old Mohsin Sheikh are still missing. Wajid's wife had told the Mumbai Police that "he started getting swayed by the extremist ideology" and was very vocal about his wish to go to Syria to join the Islamic State.