Opposition Leader Bill Shorten has launched an attack on the Adani coal mine, but declared he cannot scrap it because of sovereign risk.

Mr Shorten criticised the economical viability and environmental credentials of the proposed Queensland project, also proclaiming, "I don't like it".

But after a week of pressure to clarify his intentions, Mr Shorten admitted he cannot simply ban the mine.

"I make no secret that I don't like it very much" he said.

"But ... I also respect the principle of Australian politics. That is, one government enters into contracts, then a future Government can't just rip them up.

"To do so would be sovereign risk."

Sovereign risk, in this instance, refers to the risk of Adani being detrimentally affected by a change in the Government's policy or position.

The Opposition Leader's plans for the Carmichael coal mine have been under scrutiny ever since prominent businessman Geoff Cousins claimed Mr Shorten assured him the mine could be revoked if Labor wins government.

Sorry, this video has expired Geoff Cousins says Bill Shorten told him Labor would reconsider the Adani licence.

Today, Mr Shorten said Adani had promised too much, but delivered too little.

"I don't think the project is going to materialise, the Adani mining company seems to have missed plenty of deadlines, it doesn't seem to stack up financially, commercially or indeed environmentally," he said.

"[But] you can't simply ban it and create sovereign risk.

"No party, even the Greens political party, can simply say they can simply ban something. You've got to adhere to the law."

It had been reported by Sky News that Mr Shorten wanted to take a public stand on blocking the mine, but was talked down by senior colleagues.

Under questioning by reporters, he denied the conversation.

"No," he said.

"No prime minister can simply ignore the law. No prime minister worth their salt should simply engage in massive sovereign risk.

"We're not going to make Australia a nation who has a reputation for changing existing contracts."