Saudi Arabia is reportedly ready to concede that missing Saudi writer Jamal Khashoggi was killed in its consulate in Istanbul.

CNN reports that the Saudi government is preparing to admit Mr Khashoggi died during an interrogation that went wrong.

The report, attributed to two unnamed sources, quoted one of the sources as saying there was a plan to abduct Mr Khashoggi that was not authorized by the Saudi government.

President Donald Trump told reporters on Tuesday morning he was aware of the report, but did not know if it was correct.

One of the sources quoted by CNN said the report was still being prepared and cautioned that “things could change”.

Mr Trump said the US was working with Saudi Arabia and Turkey to work out what happened to Mr Khashoggi.

The President called Mr Khashoggi’s disappearance a “terrible situation”.

Mr Khashoggi, a critic of the current Saudi government who wrote for The Washington Post opinion pages, was last seen entering the Saudi consulate on Oct. 2.

A team of investigators entered the Saudi consulate in Istanbul on Tuesday morning for what Turkish officials called a joint inspection of the building where the writer was last seen.

Details as to what actually happened inside the consulate remain scarce, but in an interview with 60 Minutes on the weekend, Mr Trump  promised “severe punishment” if the Saudi Arabian government was proved to have executed Mr Khashoggi.

Investigators entered the Saudi consulate on Tuesday morning. Photo: Getty

Those remarks were met by a response from the Saudi Press Agency warning that it rejects any “threats and attempts to undermine” the country, and “will respond with greater action” against anyone that tries.

The Arabic-language daily Okaz later published a headline in English, warning: “Don’t Test Our Patience” accompanied by a clenched fist made of a crowd of people in the country’s green colour.

The foreign ministers of the United Kingdom, France and Germany issued a joint statement on Monday calling for an independent investigation into the disappearance.

The potential deterioration of relations between Saudi Arabia and its global trading partners would likely cost Australians at the petrol pumps.

Mr Khashoggi has not been seen since entering the consulate on October 2.

Saudi Arabia is the second-largest oil producer in the world, churning out around 10 million barrels a day, according to figures from the US Energy Information Administration.

But Saudi Arabia’s role in the global production of oil goes beyond the immense volume it currently puts out, according to BetaShares economist David Bassanese.

“The critical issue is that Saudi Arabia is the only country with enough spare capacity to offset the loss of production from Iran due to the sanctions,” Mr Bassanese told The New Daily, referring to the sanctions Mr Trump placed on Iran in May.

These sanctions are one of the reasons oil prices have been pushed to four-year highs, causing petrol prices in Australia to soar beyond $1.50 a litre.

Earlier this month the oil price spiked at US$76.41 ($107) per barrel, up from a low of US$64.24 in mid-August.