Saudi Arabia, Bahrain, the United Arab Emirates (UAE), Egypt and other countries on Monday cut diplomatic ties with Qatar, and halted all land, sea and air contact with the Gulf state, accusing it of supporting "terrorism and extremism."
Qatar "expressed its deep regret and surprise" over the countries' coordinated decision to cut relations, according to a foreign ministry statement published by Qatar-based Al Jazeera news organisation, saying the measures were "unjustified and based on false claims and assumptions."
Yemen's internationally recognised government and Libya's eastern-based government, both in countries with disputed leaderships, followed suit, and also cut ties.
TRT World's Christine Pirovolakis has more.
Qatar denies accusations
The coordinated move dramatically escalates a dispute over Qatar's support of the Muslim Brotherhood, the world's oldest Islamist movement and armed groups like Hamas, and adds accusations that Doha even backs the agenda of regional arch-rival Iran.
The dispute was triggered by a purported hack of Qatar's state-run news agency and a leak of emails between UAE and pro-Israel US lobbyists. It has spiralled since from a media war to a diplomatic crisis.
Qatar said it was facing a "campaign of lies that have reached the point of complete fabrication" aimed at putting the state "under guardianship."
"It reveals a hidden plan to undermine the State of Qatar," Al Jazeera quoted the foreign ministry as saying.
The Qatari foreign ministry said that as a member of the Gulf Cooperation Council, it was committed to its charter, respected the sovereignty of other states and did not interfere in their affairs.
TRT World editor-at-large Ahmed al Burai discusses the crisis.
Saudi Arabia's state news agency said the kingdom had decided to sever diplomatic and consular relations with Qatar "proceeding from the exercise of its sovereign right guaranteed by international law and the protection of national security from the dangers of terrorism and extremism."
Saudi Arabia said it took these decisions because of Qatar's "embrace of various terrorist and sectarian groups aimed at destabilising the region" including the Muslim Brotherhood, Al Qaeda, Daesh and groups supported by Iran in the kingdom's restive Eastern Province.
It urged other "brotherly" countries to do the same.
Later in the day, both the Saudis and the UAE stopped exports of white sugar to Qatar, the first overt sign that the diplomatic crisis is hitting food trade, trade sources said on Monday.
Qatar is dependent on the UAE and Saudi Arabia for its white sugar imports, which are estimated at less than 100,000 tonnes annually. Consumption is higher during the Muslim holy month of Ramadan, which is currently being observed.
A brief statement on the official Bahrain news agency said Bahrain, a close ally of Saudi Arabia, was also cutting air and sea contact with Qatar and was giving its citizens in Qatar 14 days to leave.
Bahrain accused Qatar of "interfering" in its internal affairs."
United Arab Emirates
UAE's state news agency WAM said the Emirates cut ties and gave diplomats 48 hours to leave the country, citing Qatar's "support, funding, and embrace of terrorist, extremist and sectarian organisations."
Abu Dhabi's state-owned Etihad Airways will suspend all flights to and from Doha from Tuesday morning until further notice. The last flight from Abu Dhabi to Doha will depart at 02:45 local time on Tuesday, the airline's spokesman said in an email. All flights on Monday will operate as normal.
Dubai-based budget carrier FlyDubai said on Monday it would also suspend flights to and from Doha from Tuesday.
The Dubai-based airline Emirates also suspended flights to Qatar starting Tuesday amid the growing diplomatic rift.
Egypt announced the closure of its airspace and seaports for all Qatari transportation to protect its national security, the foreign ministry said in a statement on Monday.
Egypt's President Sisi came into power on the back of a coup against an elected Muslim Brotherhood government.
The country will begin its ban on flights to and from Qatar on Tuesday at 6 am local time (0400 GMT), the Civil Aviation Ministry said on Monday.
"The ministry has issued a decision to halt all flights between Egypt and Qatar and to close off Egyptian airspace to Qatari aircrafts that seek to land or pass through," the ministry said.
Yemen's internationally recognised government also decided to cut ties with Qatar on Monday, accusing it of working with its enemies in the Iran-aligned Houthi movement, state news agency Saba reported.
"Qatar's practices of dealing with the [Houthi] coup militias and supporting extremist groups became clear," the government of President Abdrabbah Mansour Hadi said in a statement. Yemen's severed ties over Qatar's alleged support of groups in Yemen "in contradiction with the goals announced by countries supporting the legitimate government."
It added that Yemen supported a decision by a Saudi-led coalition fighting for more than two years to oust the Houthis from the capital Sanaa to remove Qatar from its ranks announced earlier on Monday.
Libya's eastern-based government on Monday cut diplomatic ties with Qatar, its foreign minister, Mohamed Dayri, said.
The government, which sits in the eastern city of Bayda, has little authority within Libya. It is appointed by a parliament that also sits in the east and is aligned with powerful military commander Khalifa Haftar. They have spurned a UN-backed, internationally recognised government in the capital, Tripoli.
Dayri gave no immediate explanation for the Libyan move.
Other than the statement from its foreign ministry, Qatar Airways has suspended all flights to Saudi Arabia.
Before Monday, Qatar had appeared unperturbed by the growing tensions. On May 27, Qatar's ruling emir Tamim bin Hamad al Thani called Iranian President Hasan Rouhani to congratulate him on his re-election.
The call was a clear, public rebuttal of Saudi Arabia's efforts to force Qatar to fall in line against the Shia-ruled nation, which the Sunni kingdom sees as enemy number one and a threat to regional stability.
Qatar shares a massive offshore gas field with the Islamic republic.