He is expected to receive a prison term of at least seven years.
The army has been put on standby and police say they have been given “shoot on sight” orders in case of trouble.
Singh, 50, will not be taken to court to hear his sentence. Instead, the judge who convicted him will be flown to Rohtak jail where he is being held, to deliver it.
controversial leader of the Dera Sacha Sauda sect, which claims to have 60 million followers around the world
Took over the sect – which describes itself as “a non-profit social welfare and spiritual organisation” – when he was 23
Performs at rock concerts, acts in films and even has his own line of food products
Known as “rockstar baba” and “guru of bling” because of his shiny, colourful clothes
Has been accused of mocking Sikh and Hindu figures
Has been investigated for murder and rape, charges he denies
Has been accused of forcing followers to undergo castration to “get closer to god”
The prison has been transformed into a fortress, with journalists banned within a 1.5km (one mile) radius.
There is also heavy security outside Singh’s 1,000-acre compound in Sirsa, Haryana.
Schools and colleges will remain closed. Mobile internet services were cut in Haryana last Thursday, and the ban has been extended for a further 48 hours.
Tens of thousands of his supporters are still believed to be inside the Dera Sacha Sauda sect headquarters, despite many opting to leave following a tense stand-off with soldiers.
The Dera’s Sirsa headquarters is a huge township that houses schools, a hospital and a cinema. Hundreds of soldiers and riot police had blocked approaches to the sprawling premises on Saturday, and urged those inside to leave peacefully.
A curfew imposed in Sirsa was briefly lifted on Sunday to allow the guru’s loyalists to leave the compound.
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- Rapist guru’s devotees start to leave HQ
“Violence is not acceptable in the nation, in any form,” Mr Modi said.
“Those who take law in their hands or take to violence will not be spared, whoever they are.”