N’Jie can be heard saying “I’m going to f*****g kill you... I’m going to f*****g knife you” in a shocking video which emerged after the ceremony in London on Monday night.
N'Jie, who had been nominated for the best newcomer gong, was ejected from the event at the Hilton Park Lane in Mayfair by security staff following the alleged incident.
The Emmerdale actor, who was nominated for a storyline in which his character Ellis Chapman was stabbed, but lost out to EastEnders' Kara-Leah Fernandes, is reported to have sworn and thrown punches at Lomas, 44, following the ceremony.
ITV has launched an investigation after the footage, shared by The Mirror, emerged. A spokeswoman for the broadcaster said managers planned to discuss the incident with him "in due course".
She said: "We are extremely concerned to hear about an incident at last night's TV Choice Awards involving one of Emmerdale's cast.
"Obviously we will be investigating and talking to the actor concerned in due course."
Hollyoaks star Lomas played village villain Warren Fox on and off for more than a decade in the Channel 4 soap. He also played Jake Stone on rival soap EastEnders from 2013 to 2014, and in 2017 he was the runner-up in I'm A Celebrity... Get Me Out Of Here! on ITV.
Danny Dyer won the TV Choice Award for best soap actor for the second year running while fellow EastEnder Fernandes picked up the best soap actress award.
Jed Mercurio made his mark at the annual awards ceremony as Line Of Duty sealed best drama and Bodyguard was named best new drama.
The Standard has contacted N'Jie's and Lomas's representatives for comment. Hollyoaks has also been approached for comment.