Saudi Arabia will reopen its airspace, land and sea border to Qatar as of Monday, Kuwaiti Foreign Minister Ahmad Nasser al-Sabah said on Kuwait TV ahead of a Gulf Arab summit to be held in Saudi Arabia on Tuesday.

Saudi Press Agency (SPA) quoted Saudi Arabia's Crown Prince Mohammed bin Salman as saying the annual gathering of Gulf leaders would unite Gulf ranks "in the face of challenges facing the region." 

Qatar's Emir Sheikh Tamim bin Hamad al-Thani has confirmed his attendance, the royal court said, to end the three-year-old dispute with Saudi Arabia and three other Arab countries.

The development is the latest in a series of Middle East deals sought by Washington – the others involving Israel and Arab states – aimed at building a united front against Iran.

Saudi Arabia, the United Arab Emirates, Bahrain and Egypt have imposed a diplomatic, trade and travel boycott on Qatar since mid-2017, accusing it of supporting terrorism. Qatar denies the allegation, claiming the move just aims to undermine its sovereignty.

While Saudi Arabia made clear it intended to lift the blockade, the other three countries did not do so immediately. Under the emerging agreement, Qatar will suspend lawsuits related to the blockade, the official said.

Saudi Arabia's foreign minister said a resolution to the dispute seemed within reach in December last year, while a post by Iran's Foreign Minister Mohammad Javad Zarif on Twitter said he hoped Gulf reconciliation "contributes to stability and political and economic development for all peoples of our region."

UAE Minister of State for Foreign Affairs Anwar Gargash said in a tweet that Tuesday's summit would restore Gulf unity and that "more work lies ahead and we are moving in the right direction."

On Monday, Turkey's Foreign Ministry said in a statement that it welcomed the move by Saudi Arabia and called it an important step towards resolving the dispute.

"Our hope is that this dispute reaches a comprehensive and lasting resolution based on mutual respect for the countries' sovereignty and that other sanctions against the people of Qatar are lifted as soon as possible," it said, adding that Turkey supported all efforts to bring stability to the Gulf region.

Jared Kushner, Trump's son-in-law, Middle East envoy Avi Berkowitz and Brian Hook, a special State Department adviser, were flying to the Saudi Arabian city of al-Ula to attend the ceremony, U.S. officials said.

The United States has about 10,000 troops in Qatar, which is home to the Al Udeid Air Base. There are thousands more troops in the UAE, Kuwait, Bahrain and Saudi Arabia.

(With input from Reuters)