India captain Virat Kohli on Tuesday accused Australia counterpart Steve Smith and his team of "crossing the line" by looking towards the players' area while deciding whether to review the umpire's decisions during the second test.

Smith was out leg before for 28 in the tourists' second innings off a delivery by paceman Umesh Yadav that stayed low and struck him above his left boot in front of middle stump during their 75-run defeat that levelled the series at 1-1.

Smith and partner Peter Handscomb were then caught looking towards the area outside Australia's dressing room, where television replays can be seen, while discussing whether to review the verdict, prompting umpire Nigel Llong to intervene.

Players are not allowed to have any outside input while challenging the umpires' decisions, according to the rules

An angry-looking Kohli ran towards Smith to let him know of his displeasure, as Long sent him on his way with the batsman walking towards the changing rooms amid boos from the crowd.

Kohli said it was not only time it had happened and he had already complained to the match officials about the issue during a match in which there were a number of verbal confrontations.

"I saw that happening two times when I was batting out there," Kohli said. "I pointed that out to the umpire as well that I had seen their players looking upstairs for confirmation.

"And that's why the umpire was at him (Smith). When he turned back, the umpire knew what was going on exactly. We observed that, we told the match referee and the umpire that it's been happening for the last three days and it has to stop.

"BRAIN FADE"

"There is a line that you don't cross on a cricket field. Sledging and playing on the opponents' mind is different but I don't want to mention the word but it falls in that bracket. I would never do something like that on the cricket field."

Asked by an Australian reporter if "the word" was cheating, Kohli replied: "I am not saying that, you did."

The 28-year-old Smith, ranked number one batsman in tests, received flak from former cricketers on social media. He said it was a "brain fade" from him and he should not have done it.

"I obviously got hit on the pad and looked down to Petey (Handscomb) and Petey sort of said, 'Look out there,' and I turned around and said, 'What do you reckon?'" Smith told reporters after the second test of the four-match series.

"It was a bit of brain-fade on my behalf and, yeah, I shouldn't have done that. I was looking at my boys and shouldn't have done that. I think it was the first time it's happened."

On-field sledging was a big topic before the series, with both teams led by demonstrative captains in Kohli and Smith.

India and Australia share an acrimonious past on the cricket field and tempers had been running high during the second of the four-match test series between the world's top two ranked sides, needing interventions from the umpires to calm the players down.