Alleging that the West Bengal government has conspired against the GJM to break up its movement for a separate state of Gorkhaland, he told a party rally in Darjeeling, “If a CBI investigation is not ordered into Tamang’s killing, I will go on a fast.”

Gurung had threatened to retaliate on Tuesday if his party workers were attacked in the wake of anti-GJM sentiments triggered by the killing of the Gorkha leader. He said he would prove that he still enjoys mass support at a public rally scheduled to be held in Darjeeling on Sunday.

Meanwhile, GJM activists braved rains to attend the rally in Kurseong, which was attended by party publicity wing chief Harkabahadur Chhetri, who quietly returned to the party a day after announcing that he was quitting in protest against Tamang’s murder as the needle of suspicion pointed towards the GJM.

In Kolkata, Director General of Police Bhupinder Singh said an FIR has been filed against Gurung for holding a meeting in Darjeeling on Tuesday where prohibitory orders are in force.

The GJM, however, took formal permission for its rally in Kurseong today, he said. The GJM seeking permission for Sunday’s meeting at Darjeeling would be reviewed before a decision was taken, Singh said.

Meanwhile, CID began its investigation into Tamang’s killing.

“We have got some clues on the murder,” he said, terming the reports of some foreigners having videographed the killing as rumours.

“If the allegations against those named in the FIR are proved, they will be arrested, but strong evidences are required,” Singh said.

In another development, the All India Gorkha League met last night and appointed Tamang’s widow Bharati as the party’s new chief.