Saudi Aramco's initial public offering will take place in the second half of 2018, CEO Amin Nasser said Monday, dismissing reports that the oil giant's plans could be shelved.

"We have always said that we will be listing in 2018, and to be more specific, in the second half of 2018," Nasser said in an interview with CNBC television. 

"The IPO is on track. The listing venue will be discussed and shared in due course," Nasser told the channel in Riyadh.

The Aramco chief also said Saudi authorities were not in talks with Chinese or other investors to sell a stake in the firm, estimated to be worth around $2 trillion.

Aramco, which controls Saudi Arabia's massive energy assets, plans to list nearly five percent of its shares in the stock market. 

The IPO is expected to be the largest in history, raising around $100 billion in much-needed revenue for the kingdom, which has posted $200 billion in deficits in the past three fiscal years.

The listing is a cornerstone of an ambitious economic reform programme launched by powerful Crown Prince Mohammed bin Salman last year.

The programme, known as Vision 2030, aims to balance the Saudi budget after the OPEC kingpin lost hundreds of billions of dollars due to the slump in oil prices.

Doubts have been swirling around the viability and ambitious timeline of the Aramco IPO. 

Saudi Arabia had laid out plans for a dual listing on the Saudi stock market and an international exchange for 2018, with markets in New York and London vying for the offering.

But the company has struggled to select an international venue for its listing.