Reports say Saudi Arabia, the United Arab Emirates, Egypt, Bahrain, Yemen and the Maldives are severing diplomatic relations with Qatar.
The Saudi kingdom made the announcement via its state-run Saudi Press Agency early on Monday, saying it was taking action for what it called the protection of national security.
The news agency released a statement in which it accused Qatar of “harbouring a multitude of terrorist and sectarian groups that aim to create instability in the region”.
Reports say the three Gulf states gave Qatari visitors and residents two weeks to leave their countries.
Saudi also closed the border and halted air and sea traffic with Qatar, urging “all brotherly countries and companies to do the same”.
The statement appeared to be timed in concert with an earlier announcement by Bahrain, which was similarly cutting ties and halting air and sea traffic between the two countries.
Qatar’s foreign ministry said it regretted the measures by the Arab nations, calling the decisions “unjustified”.
“The measures are unjustified and are based on claims and allegations that have no basis in fact,” the statement said, adding that the decisions would “not affect the normal lives of citizens and residents”.
“The aim is clear, and it is to impose guardianship on the state. This by itself is a violation of its [Qatar’s] sovereignty as a state,” it added.
Bahrain’s foreign ministry issued a statement saying it would withdraw its diplomatic mission from the Qatari capital, Doha, within 48 hours and that all Qatari diplomats should leave Bahrain within the same period.
The UAE said in a statement it was cutting off all ties with Qatar. It also ordered Qatari citizens to leave the country within 14 days and banned its citizens from travelling to Qatar.
Reports say Egypt through a statement from its foreign ministry also announced the closure of its airspace and seaports for all Qatari transportation “to protect its national security”.
Later on Monday, the Maldives said in a statement that it took the decision to sever diplomatic ties “because of its firm opposition to activities that encourage terrorism and extremism”.
UAE-based carriers Emirates, Etihad Airways and FlyDubai said they would suspend flights to and from Qatar beginning Tuesday morning.
It was not immediately clear how Monday’s announcement would affect other airlines.