Saudi Crown Prince Mohammed bin Salman gave South Korean President Yoon Suk Yeol a ride to a high-profile investment conference in Riyadh on Tuesday, saying he hopes the two will be able to ride in a locally produced Hyundai car next time, according to Yoon's office.

Yoon was on a four-day state visit to Riyadh from Saturday to Tuesday and was set to head to the annual Future Investment Initiative forum to deliver a speech.

The crown prince made a surprise visit to Yoon's guest house at around noon. The two leaders talked for about 20 minutes before the crown prince took the president in his car and drove 15 minutes to the FII conference, according to the presidential office.

"Next time you come, I hope we will be able to ride together in a Hyundai electric vehicle manufactured in Saudi Arabia," the crown prince was quoted as saying.

South Korea's Hyundai Motors and Saudi Arabia's Public Investment Fund signed a contract on the occasion of Yoon's state visit to jointly invest around $400 million in the construction of a car assembly plant in King Abdullah Economic City in Makkah Province, Saudi Arabia.

The plant will be designed to produce 50,000 electric and gas-powered cars annually starting in 2026, becoming South Korea's first electric vehicle production hub in the Middle East and an entry point for the wider Middle Eastern and North African markets, according to the presidential office.

Crown Prince Mohammed joined Yoon at the conference where he was to give his speech and stayed until the end of the event, the presidential office said. (Yonhap)