Aramco is “ready” for the giant stock market debut but the timing is a “government decision”, Amin Nasser told reporters on the sidelines of the World Energy Congress. “One of the primary listings is going to be local but we are also ready for listing outside”, he added.

Nasser's remark came after the Wall Street Journal reported last week that Aramco was considering a domestic debut and a subsequent international listing – possibly in Tokyo.

Aramco has said it plans to float around five percent of the state-owned company in 2020 or 2021 in what could potentially be the world's biggest stock sale.

The planned IPO forms the cornerstone of a reform program envisaged by the kingdom's de facto ruler Crown Prince Mohammed bin Salman to wean the Saudi economy off its reliance on oil.

It aims to raise up to $100 billion based on a $2 trillion valuation of the company, but investors have long debated whether Aramco is really worth that much.