Saudi Arabia's powerful crown prince and a delegation of ministers arrived in neighbouring Qatar on Sunday morning to attend the opening ceremony of the World Cup, Saudi state media reported.
Mohammed bin Salman was accompanied by the kingdom's energy, interior, foreign, commerce and investment ministers as well as senior officials including his national security adviser and head of the National Guard, the official Saudi Press Agency said.
Prince Mohammed also ordered all government ministries and agencies "to provide any additional support or facilities required by Qatar" to host the event, the sports ministry said in a statement, without providing details.
Prince Mohammed, Saudi Arabia's 37-year-old de facto ruler, orchestrated a regional blockade of Qatar beginning in June 2017, the same month he became first in line to the throne.
Saudi Arabia, the United Arab Emirates, Bahrain and Egypt cut ties with Doha over allegations it supported extremists and was too close to arch-rival Iran -- allegations Doha denied.
The quartet agreed to lift the restrictions at a Gulf Cooperation Council summit in January 2021 in the Saudi city of Al-Ula.
Prince Mohammed travelled to Qatar in December of last year and, along with its emir Sheikh Tamim bin Hamad Al Thani, visited Lusail Stadium, which will be the venue for the final of this year's World Cup.
It was not immediately clear how long Prince Mohammed, who recently completed a multi-country tour of Asia, intended to stay in Qatar.
Saudi Arabia is scheduled to play its first group match in the World Cup against Argentina on Tuesday.
The kingdom is putting on 240 flights a week to Qatar, up from six normally, and easing overland travel to attract tens of thousands of football fans attending the World Cup, the tourism minister told AFP last month.