A 30-year-old man who was allegedly swinging swords that "motivated" the protesters at the Red Fort during the violence in Delhi on Republic Day has been arrested, police said on Wednesday.

Maninder Singh, who works as a car AC mechanic, was arrested around 7.45 pm on Tuesday near the C D block bus stop in Pitampura in northwest Delhi.

"Singh was seen in a video swinging two swords at Red Fort with intent to motivate or radicalise and energise the violent anti-national elements indulging in brutal assault or attack on police persons on duty with swords, 'khandas', iron rods, axes, 'barsaas', sticks etc and damaging historical monument Red Fort on Republic Day," Deputy Commissioner of Police (Special Cell) Pramod Singh Kushwah said.

The suspect, who runs a sword-training school in an empty plot near his house in Swaroop Nagar, has "disclosed to have been radicalised by seeing provoking Facebook posts of various groups. He used to frequently visit Singhu Border and was highly motivated by speeches made by leaders there", police said.

Thousands of protesters had clashed with the police during the tractor parade called by farmer unions on January 26 to highlight their demand for repeal of the Centre's three farm laws. Many of the protesters, driving tractors, reached the Red Fort and entered the monument. Some of them even hoisted religious flags on its domes and the flagstaff at the ramparts.

According to police, Singh had "motivated" six people of the neighbourhood. All six of them, riding upon bikes, had accompanied tractor rally of farmers heading from Singhu border towards Mukarba Chowk on Republic Day.

Before joining tractors parade, Maninder had kept two swords with him -- 'khandas' having a size of 4.3 feet -- that were used in swinging at Red Fort. The swords have accused recovered from his house, police said.

As per their plan, the suspect and with his five associates and other unknown armed miscreants entered the Red Fort and he did sword dance or swing.

"That sword dance had motivated violent protesters to cause more mayhem at Red Fort by indulging in all sorts of violence against public servants, including policemen on duty there, and causing damage to historical monument of Red Fort," Kushwah said.

A long video of him purportedly swinging swords at Red Fort on January 26 has been found in his mobile phone. Other photos of his presence at Singhu border are in his phone, police said, adding that an investigation was on.