The Northern Territory chief minister has defended his record on addressing juvenile detention, repeatedly emphasising that a number of controversial incidents occurred under the previous Labor government.

But Adam Giles also admitted he only inspected the beleaguered and controversial Don Dale facility for the first time on Tuesday morning, despite it having opened in 2014 and hosting a string of highly controversial incidents.

Giles was addressing the national furore around the treatment of children in the Northern Territory’s Don Dale youth correctional facility, after Four Corners aired shocking footage of abuse of detainees by guards.

The prime minister, Malcolm Turnbull, announced a royal commission on Tuesday morning, following on from a number of NT inquiries since 2011 which had failed to prompt real change. After the program Mick Gooda, the Aboriginal and Torres Strait Islander justice commissioner, called for the federal government to sack the NT government.

Appearing on The Bolt Report on Sky News, Giles told host Andrew Bolt the series of reviews into the system enabled his government to enact improvements.

“I think we’re getting to a much better place right now in youth detention,” he said. “There’s no doubt the system we inherited was existing under a culture of coverup and a shroud of lack of confidence, particularly around the treatment of some of the young kids.”

When Bolt noted his government had been made aware of multiple incidents, Giles said the issues had to be “put into context” and often actions were taken for the safety of individual detainees and centre employees.

Asked specifically about the use of the restraint chair, Giles said it formed part of the review he would like to see the royal commission undertake, “to identify appropriate measures for restraint”.

Just three months ago the Giles government passed legislation which widened the use of mechanical restraints, including specifically the chairs.

Despite at one point saying it didn’t matter to the issue who was in charge, Giles repeatedly pointed to incidents which occurred under the previous Labor government. He also drew a link to the Northern Territory intervention launched during the Labor administration, and at the end of the interview said “the Labor party in the Northern Territory has a lot to answer for” and accused them of throwing mud and stones.

Speaking later to ABC News NT, Giles said he was shown footage by Four Corners of incidents that preceded his government.

“I’m not apportioning blame, but … these were all issues I hadn’t seen before, they were issues before I came to government”, he said.

The Lateline host, Emma Alberici, later asked Giles on ABC how he could be shocked by the reports given the amount of media coverage of incidents over the years.

“There were some things we were aware of and some things we weren’t. The elements of the incident of children being gassed most definitely we were aware of at the time. But the incidents about children being struck or demonised or thrown down I wasn’t aware of that. Those images were taken well before we came into government and it’s not something we had made ourselves aware of.”

At least one of the clips – that of Dylan Voller being stripped and physically held down by guards while in his cell – has been in the public domain since 2014, forming part of an ABC news report.

Giles dismissed suggestions there was any racial aspect to the controversy. “There is definitely no policy particularly against Aboriginal people,” he said.

“But what we saw in that footage last night was some elements of poor custodial practices, most horrific. It’s one of the issues we’ve been dealing with for three and and a half years in the corrections system. I think the biggest culmination of that was in the gassing incident.”

He declined to say he could guarantee children in Don Dale right now were safe from harm. “What I can guarantee is that the corrections system in the Northern Territory is much better than it was four years ago. There have been a number of reviews undertaken and hopefully another one tabled later this week looking at the corrections system in the Northern Territory and its practices.”

He also declined to answer if he had read the children’s commissioner’s report. He said the government had put in place all 16 recommendations from the Vita review.

“Don Dale is a much better centre now than it was four years ago, but looking back on that footage last night, much of that footage was new to me, it was historic.”

Addressing his claims about a “culture of coverup”, Giles said “upper echelons of government weren’t always provided with all elements of information”, pointing, again, to footage of incidents during the previous government.

The tear-gassing was described to the public by government and corrections department at the time as a response to a “riot” by several boys. The children’s commissioners report and CCTV footage later revealed this to be false, with just one youth escaping.

Delia Lawrie, the former Labor attorney general, rejected Giles’ claims they knew nothing and said he had allowed Elferink to preside over “a system of brutality”.

But she also said she had no awareness of the incidents and allegations when she was attorney general.

“I want to know … who knew what where and when,” she told ABC radio on Wednesday. “That royal commission, thank god will tell us.”

Giles also denied sacking minister for justice and corrections, John Elferink, who is also the attorney general.

“I never sacked John Elferink, I said I was taking control of his portfolios,” he told ABC.