Several cities in northern India are under a security lockdown ahead of tomorrow's verdict in a rape trial involving controversial and hugely popular spiritual leader Gurmeet Ram Rahim, who has been accused of sexual harassment by two of his female followers.

Tens of thousands of followers of the flamboyant guru and leader of the quasi-religious sect Dera Sacha Sauda have gathered in the town of Panchkula where a Central Bureau of Investigation's (CBI) special court is set to announce the verdict on Friday.

The guru, who calls himself Saint Dr Gurmeet Ram Rahim Singh Ji Insan, has denied the charges of raping two of his female followers. The case was investigated by CBI, India's top agency.

The self-styled guru was also under investigation in 2015 for allegedly encouraging 400 followers to undergo castrations at his ashram so they could get closer to God.

Men and women, some with children and babies, have spread out blankets and bed sheets, and settled down around the court complex, which is surrounded by security, to wait for the verdict.

Nearly 6,000 police and paramilitary soldiers have spread out in Panchkula alone and thousands more have fanned out in nearby areas fearing violence in the event of a guilty verdict. More troops have been kept on standby.

In Panchkula and the neighbouring city of Chandigarh, three sports stadiums have been set aside to act as makeshift prisons in case of violence, police said.

Chandigarh has also sealed its border for the next two days to prevent the violence from spilling over.

On Thursday, police were checking all vehicles entering Haryana state where both the court house and the guru's ashram are located.

Local administrators have asked that schools, colleges and offices remain closed on Thursday and Friday. All public transport in and around the town will also remain off the roads.

Religious sects like the Dera Sacha Sauda have huge followings in India. It's not unusual for leaders of these sects to often have small, heavily armed private militias protecting them.

The sect claims to have 50 million followers and runs a spiritual empire that promotes vegetarianism and campaigns against drug addiction.

In 2007, clashes between the Dera Sacha Sauda followers and members of the Sikh faith in northern India had left at least three people dead.

In 2014, six people were killed as followers of another popular religious leader, guru Rampal, fought pitched battles with police who were attempting to arrest him for contempt of court after he repeatedly failed to appear in court in connection with a murder trial.