The attacker, a non-Namdhari Sikh, was arrested after the incident yesterday and is currently in custody.
"Officers attended the scene where Sri Satguru Uday Singh Ji, the spiritual head of the Namdhari community worldwide, was found to have been assaulted," a Leicestershire Police statement said.
"A 26-year-old man was arrested at the scene and remains in police custody. At this time police believe it was an isolated incident, which was carried out by a single perpetrator."
"Guruji is recovering fast and was discharged from hospital yesterday. The facial injuries are not that serious but he has fractured his right wrist," he said.
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Though police did not reveal the attacker's identity, Ranjit Singh said the accused was a Sikh man but not from the Namdhari sect.
"At this stage, we would not like to speculate further but he may have been instigated by someone known to the sect," he said.
According to reports, the attacker was caught by members of the congregation present for the prayers.
The sect leader deflected the attack but suffered injuries to his face and arm. He was taken to the Royal Infirmary in Leicester and was discharged following stitches to his nose and treatment of his broken wrist.
Singh took over as the Namdhari sect leader in December after the death of Satguru Jagjit Singh. His selection triggered some controversy within the sect.
He had travelled to the UK from India to convene a Namdhari Darbar.