The chair of a parliamentary committee examining Rio Tinto’s destruction of 46,000-year-old rock shelters at Juukan Gorge in the Pilbara says the company appears to have misled the inquiry.

“It is hard to argue that we have not been misled by Rio Tinto’s evidence to the inquiry when you look at what was said together with the documents the company has provided on notice,” Queensland LNP MP Warren Entsch told Guardian Australia.

“It is a profound statement to say that senior executives did not know when the company has been aware since the early 2000s of the significance of the caves.”

Entsch’s attack came as the parliamentary inquiry was forced to indefinitely delay a planned site visit to Juukan Gorge – a decision the traditional owners, the Puutu Kunti Kurrama and Pinikura (PKKP) people, said would “rob us of a voice in the proceedings”.

The chair’s comments add to pressure from investors and activists for the board of Rio Tinto, which is believed to be meeting this week, to sack chief executive Jean-Sébastien Jacques over the Juukan Gorge debacle.

“If you look at Jacques’ responses to the inquiry it’s hard to come to any other conclusion [than it has been misled],” Entsch said. He also warned other mining companies that they were on notice about the importance of protecting Indigenous heritage sites.

“Using the example of Rio Tinto, they would be very, very cautious, or be very, very foolish to barge ahead on mining now, they can’t plead ignorance as a defence,” he said. “There is a lot of international attention on this, and companies would exercise caution under those circumstances.”

The two rock shelters were blown up by Rio Tinto on 24 May as part of the expansion of the Brockman 4 iron ore mine in Western Australia’s Pilbara region.

An archeological survey, paid for by Rio, found that one of the shelters had been continually occupied over 46,000 years and was of the “highest archeological significance in Australia”.

The full significance of the site emerged after Rio Tinto received permission from the WA government in 2013 to destroy the sites. An internal review found that despite receiving the preliminary archeological report in 2014, the full archaeological report in 2018, and two further ethnographic reports detailing the significance of the site to the PKKP peoples, no one at Rio flagged it as a potential risk.

Jacques told the parliamentary inquiry into the destruction of the sites that he was informed, three days before the blast, of a “potential issue” at the Brockman 4 iron ore mine in the Hammersley ranges.

But he said he did not learn the significance of the Juukan Gorge rock shelters until the night of Sunday 24 May – after they have been destroyed.

Entsch said Rio Tinto’s reports on Juukan Gorge weren’t done with “petty cash”.

“Archaeological surveys are very, very substantial matters,” he said. “Rio then funded a doco on the significance of the caves, featuring the PKKP. I don’t know, I haven’t made a doco, but it costs a bit more than tea money. Somebody must have written the cheque, it wouldn’t have been out of the tea money.”

“I chair a committee here that has representatives across the political spectrum, and the committee is as one, we are as one on dealing with this and getting to the bottom of it.”

Meanwhile, the chair of the PKKP Aboriginal corporation, John Ashburton, said that the decision to delay on-country hearings because of coronavirus travel restrictions would prolong the investigation which “only serves to further deepen our hurt and anguish”.

“This decision serves to rob us of a voice in the proceedings,” chair John Ashburton said. “To date, Rio Tinto and others have been given a voice and public stage to present their views on the disaster. The same courtesy has been denied to us by this delay.”

The deadline for the inquiry to make its final report has been pushed back from 30 September to 9 December.

“The community deserves the full facts of the Juukan Gorge disaster be told in a timely manner to ensure this kind of tragedy never happens again,” Ashburton said.

The National Native Title Council (NNTC) earlier joined calls for an overhaul of the Rio Tinto board to include more Australian directors.

In a letter to chairman Simon Thompson, NNTC chief executive Jamie Lowe said Rio Tinto’s appearance before the Senate inquiry and its roundly criticised internal review showed the company had misled the public by blaming failures in “linked-up decision making” for the destruction of an ancient place.

Lowe said Rio made “active decisions” to support the blast going ahead, like hiring lawyers against a potential injunction.

“It is now clear that what led to the catastrophic destruction of Juukan Gorge was not a result of a breakdown of procedures but a result of the enormous cultural and values deficit within Rio Tinto,” he said.

Throughout his evidence to the parliamentary inquiry, and in the 84-page response to questions on notice provided last week, Jacques appeared to put the blame for his ignorance of the potential ramifications of destroying such a heritage-listed site against the wishes of traditional owners back on Perth-based chief executive of iron ore, Chris Salisbury.

He said that when he spoke to Salisbury prior to the blast “there was no mention of the cultural heritage issue, the issue was a question of timing and a request by the PKKP”.

The minutes of two meetings held in the days before the blast show Salisbury was concerned not about damaging Juukan Gorge but about the potential legal risk of damaging other Aboriginal heritage sites, which the company did not have permission from the Western Australian government to disturb.

Rio’s initial public response said it had “all necessary approvals” to destroy the site and was “sorry that the recently expressed concerns of the PKKP did not arise through the engagements that have taken place over many years”.

It moved to offer a genuine apology a few weeks later after a backlash from investors. Ratings agency S&P said the Juukan Gorge saga, together with controversy over plans by BHP and Fortescue Metals Group to blast heritage sites, “highlights the fact that social risk factors go beyond legal obligations”.

“Any company looking to develop a new project or expand an existing one will need to ensure all stakeholders are satisfied – above and beyond what government legislation stipulates you can or cannot do,” the S&P global ratings director, Minh Hoang, said.

“A major investor sitting in London is less interested in the efficacy or otherwise of local government legislation on the other side of the world. But rightly or wrongly, the investor will be concerned about how things ‘look’ to the wider market and community.”

S&P thinks this could result in mining projects taking longer to get started.

“Mining companies will undoubtedly be circumspect when developing projects. They will look to work with local communities to avoid important heritage sites; they will not want to incur investor wrath.”