Assam police on Wednesday registered a case against “Mizoram police and some persons” over the killing of six Assam cops in the inter-state border clash on July 26, hardening their stand amid efforts by the Union home ministry to ease the tensions.

Assam special director-general of police G.P. Singh said the FIR was filed under various sections of the IPC, including Sections 302 (murder) and 307 (attempt to murder). Singh said Assam police had also prepared a picture gallery of the Mizoram cops and civilians who had opened fire.

On Wednesday, the chief secretaries and DGPs of Assam and Mizoram attended a meeting chaired by Union home secretary Ajay Kumar Bhalla in New Delhi. It was decided that central armed police forces would be deployed on the inter-state border.

The two states will work out an arrangement in coordination with the Union home ministry within a reasonable timeframe to facilitate the functioning of the neutral force, a statement signed by Assam chief secretary Jishnu Barua, his Mizoram counterpart Lalnunmawia Chuaungo and Union home ministry additional secretary (Northeast) Piyush Goyal said.

Mizo Students’ Union president J. Lalmuanzuala on Wednesday wrote an open letter to Assam chief minister Himanta Biswa Sarma, accusing him of having “initiated violence against civilians in Mizoram knowing fully well that your actions can hamper the cordial relationship we have with the Indian Union for your selfish motives to take away the land that our ancestors had fought for through blood and sweat. This has led to the unfortunate loss of seven precious lives.”