Full ties have been restored between Qatar and the four nations that severed relations with Doha in a rift that began in 2017, Saudi Arabia's Foreign Minister said Tuesday.

"What happened today is... the closure of the folder of all points of difference and a full return of diplomatic relations," Prince Faisal bin Farhan told a press conference at the conclusion of a landmark regional summit.

Leaders of the six-member Gulf Cooperation Council signed two documents, the Al-Ula declaration, named after the Saudi city where the summit was held, and a final communique.

Their contents were not immediately released but hopes for a deal to end the bitter impasse were raised overnight when Saudi announced it would open its borders to Doha despite lingering enmity between the neighbours.

"These efforts helped us reach the agreement of the Al-Ula statement that will be signed at this summit, where we affirm our Gulf, Arab and Islamic solidarity and stability," he told the meeting, thanking the United States and Kuwait for their mediation.

"There is a desperate need today to unite our efforts to promote our region and to confront challenges that surround us, especially the threats posed by the Iranian regime's nuclear and ballistic missile programme and its plans for sabotage and destruction."

The summit was also attended by Egypt's Foreign Minister Sameh Shoukry.

Saudi Arabia, Egypt, the United Arab Emirates (UAE) and Bahrain cut ties and transport links with Qatar in June 2017, accusing Doha of backing radical Islamist groups and cooperating with Iran. Qatar has always denied these allegations.