India's Ravichandran Ashwin has condemned fans after team-mate Mohammed Siraj suffered alleged racial abuse on day four of the third Test between Australia and India.

Cricket Australia has launched an investigation after six spectators were ejected from the Sydney Cricket Ground in response to allegations of racist abuse against India players.

Indian paceman Siraj complained to the umpires and pointed to a section of the crowd near where he had been fielding at fine leg on Sunday.

Police and security guards were called in and later escorted six people from the stadium, as play was held up for almost 10 minutes.

"They have been quite nasty, they have been hurling abuses as well, but this is the time they have gone one step ahead and used racial abuse," all-rounder Ashwin told Sky Sports.

"There was an official complaint lodged yesterday, and the umpires also mentioned it to us that we must bring it to their notice as soon as it happens, on the field, and then they will be able to take action.

"It is definitely not acceptable in this day and age. We have seen a lot, right? We have evolved as a society. This must be definitely dealt with an iron fist. And we must make sure that it doesn't happen again.

"Personally I think Adelaide and Melbourne weren't as bad. But this has been a continuous thing at Sydney. I have experienced it as well. They do tend to get nasty. I don't know why and for what reason.

"Unless and until it is dealt with, people don't find the reason to look at it in a different way.

"In fact I was quite surprised that some sections of the crowd continuously did it and they were no mates around them to pull them up for it. It definitely had to be dealt with. Disappointing is a very, very mild word, I must say."

Indian team representatives alerted officials following the third day's play that players, including Siraj and Jasprit Bumrah, were subjected to abuse – including that of a racist nature – from members of the crowd, which is restricted to 25 per cent capacity due to Covid-19.

India captain Virat Kohli, who returned home for the birth of his first child after the opening Test of the series, also condemned the abuse.

He wrote on Twitter: "Racial abuse is absolutely unacceptable. Having gone through many incidents of really pathetic things said on the boundary Iines, this is the absolute peak of rowdy behaviour. It's sad to see this happen on the field.

"The incident needs to be looked at with absolute urgency and seriousness and strict action against the offenders should set things straight for once."

Australia coach Justin Langer was critical of fans and told a press conference: "I have hated it as a player, I have hated it as a coach. We have seen (it) in different parts of the world, it is really sad to see this happening in Australia."

Cricket Australia, in a statement, said: "Play was halted for several minutes after the Indian team made a complaint regarding abuse from a section of the crowd in the Brewongle Stand concourse.

"A number of spectators were interviewed by NSW Police and ground officials and subsequently removed from the ground."

Sean Carroll, Cricket Australia's head of integrity and security, said: "The abuse of cricketers by crowd members is not acceptable. We thank the Indian team for their vigilance in reporting today's incident which we are now investigating. As hosts, we once again apologise to the Indian team."

The International Cricket Council issued a statement in which it said it "strongly condemned reported incidents of racism" during day four and had offered Cricket Australia "all necessary support in investigating the incidents."

ICC chief executive Manu Sawhney said:  "There is no place for discrimination in our sport and we are incredibly disappointed that a small minority of fans may think that this abhorrent behaviour is acceptable.

"We have a comprehensive anti-discrimination policy in place that members have to abide by and ensure is adhered to by fans and we welcome the action taken by ground authorities and Cricket Australia today.

"We will provide Cricket Australia and the relevant authorities with our full support in any ensuing investigation as we will not tolerate any racism in our sport."

Australia are poised to regain the series lead after losing the second Test in Melbourne, setting India 407 to win.

With India dismissed for 244 on day three in response to Australia's 338, the home side declared their second innings on Sunday at 312 for six. Steve Smith followed his first innings 131 by making 81, while Cameron Green scored 84.

India closed on 98 for two, still needing 309 runs to win, after openers Rohit Sharma (52) and Shubman Gill (31) were dismissed by Pat Cummins and Josh Hazlewood.