Security agencies in a sweeping operation have arrested four suspected terrorists belonging to the ISIS Khorasan module which spans five states and was allegedly plotting a major strike.

The crackdown against the Islamic State-inspired unit was conducted by the Delhi special cell, the anti-terrorism squads of Uttar Pradesh and Maharashtra, as well as the police of Andhra Pradesh, Punjab and Bihar.

Simultaneous raids were carried out in Mumbra (Maharashtra), Jalandhar (Punjab), Narkatiaganj (Bihar), as well as Bijnor and Muzaffarnagar (both in Uttar Pradesh).

Khorasan group was formed by senior al-Qaeda members operating in ISIS-controlled Syria and now looks to have infiltrated in India

Six other suspects were taken into custody for interrogation.

The Khorasan group was formed by senior al-Qaeda members operating in ISIS-controlled Syria and reportedly has a small number of fighters.

Its leaders are based in Bawabiyah, Aleppo and its primary area of operation is northwestern Syria, though it has been recruiting heavily in other countries, including India and Pakistan.

UP ATS chief Aseem Arun said that the accused were planning to launch a major terrorist attack in the country.

Mufti Faizan and Tanveer, who are allegedly connected with ISIS, were arrested from Bijnor.

India boosted security at the Taj Mahal after another pro-Islamic State group reportedly warned of attacks in the country and threatened the 17th century monument last month

Nazim Shamshad Ahmed (26), from Bijnor, was nabbed in Mumbra township of Thane district adjoining Mumbai, and Muzammil was apprehended from Jalandhar.

Arun confirmed that six people have been taken into custody and are being questioned in Noida.

'Three accused will be produced in a Noida court where the ATS will seek their transit remand to take them to Lucknow. Important documents related to ISIS were seized from them,' he said.

The operation followed a March 7 encounter in Lucknow in which a suspected terrorist belonging to the Khorasan module was killed.

Intelligence agencies has also reports that the Islamic State is making efforts to recruit youths from India

The official said the youths arrested were not directly working for any group: they are self-motivated, self guided and self-radicalised.

A top source told Mail Today: 'They got in touch with each other over the internet and the security agency intercepted a keyword "Bada Kaam", which was their future plan to carry out a strike in the country. They were being readied to carry out terror activities in the country. However, these youths are misguided and so far have not directly been involved in any terror activity and will deradicalised.'

Officials have of late intensified operations to track down and nab such terrorists following a clutch of attacks on railways infrastructure purportedly by groups linked to the global terror outfit.

Mail Today broke the story last month about how India's most populous state, UP, is turning into a breeding ground for Islamic State.

About 15-20 youths are being deradicalised by the ATS, while over 100 sympathisers are under surveillance of several security agencies.

The reasons behind this surge in numbers are high Muslim population, unemployment and a rash of communal violence in the state.

Even in the recent crackdown, evidences of self-indoctrination through the web were discovered.

'We have also found that they were definitely influenced by the material available on the internet,' UP ADG (law & order) Daljit Chaudhary said in Lucknow.

Investigations show that one of them wanted to finance the group and they were continuously communicating with each other about carrying out some major strike in the near future.

Cops claim that those arrested were suspected to be looking for potential recruits in Bihar, UP and Maharashtra.

The ATS had received intelligence that some known terror suspects in western Uttar Pradesh had become active and were hiring new members.

The police and intelligence agencies are keeping a close watch on cyberspace and communication through WhatsApp, Viber and other chat rooms to keep abreast of attempts to indoctrinate the youth.

According to a senior official, these self-radicalised suspects are the biggest worry as it is difficult to track them.