With an aim to revive terrorism in Punjab, Pakistan's external spy agency ISI has been the brain behind pushing Khalistani leader Amritpal Singh back to India with the help of overseas Sikh separatists, the officials said on Saturday.

Singh, 30, was a truck driver in Dubai before the ISI, with the help of Khalistan supporters based outside India, radicalized him so that he could plunge Punjab again into the dark days of terrorism, they said as quoted by news agency PTI.

The radical Sikh preacher had been openly making statements about declaring secession from India and forming Khalistan, threatening Union Home Minister Amit Shah and Punjab CM Bhagwant Mann. He spoke about former prime minister Indira Gandhi and chief minister Beant Singh who were assassinated by terrorists.

While Gandhi was shot dead by her own guards, Beant Singh was killed by Dilawar Singh, who acted as a human bomb. The radical preacher claimed that many Dilawars were ready in the current scenario of Punjab.

The officials said that Singh also incited the Sikh youths to resort to armed rebellion against the democratically elected governments in order to oppose the supposedly discriminatory treatment being mete to achieve the ‘ultimate goal’ of the formation of Khalistan.

Addressing a function at Rode in Punjab's Moga district, Singh had earlier said that governments run by non-Sikh have no right to rule over the people here and they must be ruled over only by Sikhs, PTI reported.

He has been styling himself on the lines of terrorist Jarnail Singh Bhindranwale, who was killed during Operation Blue Star in 1984, by copying his attire, and mannerisms, carrying an arrow, keeping a battery of armed bodyguards, and taking the shield of religion.

In addition, Singh is also alleged to have links with Lakhbir Singh Rode, head of the International Sikh Youth Federation who is sought for trial in India and wanted in cases of Arms Smuggling (including RDX explosives), conspiracy to attack government leaders in New Delhi and spreading hatred in Punjab.

Having made his comeback to Punjab at the behest of ISI, Singh took the help of Amrit Sanchar to set up his organization. Later he launched a campaign called ‘Khalsa Waheer’ and strengthened his organization by going to the villages, they said.

He stirred up the issues of Punjab and started inciting the Sikhs against the government by invoking religion.

"The lower strata of society and aimless youth became an easy target of Singh and he started exploiting the sentiments in the name of religion," a source told PTI.

They stated that his main aim was to push Punjab towards dark decades of militancy which have been overcome by great difficulty and a lot of sacrifices. The officials claimed that the organization headed by Singh was getting funds from Pakistan.

The radical Sikh preacher had taken over the control of accounts of Waris Punjab De with the help of his uncle Harjit Singh, thus making it a family-run organization.