President Yoon Suk Yeol and first lady Kim Keon Hee leave the plane after arriving back in Korea, Thursday, Oct. 26. Yonhap

President Yoon Suk Yeol returned home Thursday from a series of state visits to Saudi Arabia and Qatar, where he focused on diversifying economic cooperation and unlocking new business opportunities for Korean firms.

On a four-day state visit to Riyadh, Yoon held a summit with Saudi Crown Prince Mohammed bin Salman and agreed to deepen the future-oriented strategic partnership between the two countries.

A total of 51 deals and memorandums of understanding (MOU) worth US$15.6 billion were signed, including in the sectors of crude oil, hydrogen energy, statistics, food and medical products.

Among them was a contract between the state-run Korea National Oil Corp. and Saudi Arabia's state-run oil giant, Saudi Aramco, to create a joint crude oil reserve of 5.3 million barrels in the Korean city of Ulsan.

In Doha, Yoon held a summit with Qatari Emir Sheikh Tamim bin Hamad Al Thani, and the two sides agreed to upgrade their relations to a "comprehensive strategic partnership."

The two-day state visit led to the signing of a $3.9 billion contract between Korea's HD Hyundai Heavy Industries and Qatar's state-owned petroleum company QatarEnergy for the construction of 17 liquefied natural gas (LNG) carriers.

The contract was the largest ever for Korea's shipbuilding industry and increased South Korean companies' share of the world's LNG carrier orders this year from 74 percent to 81 percent, according to the presidential office.

In addition, 11 MOUs were signed in a range of sectors, including smart farming, solar energy, driverless cars, cultural content, medical services and finance. (Yonhap)