The United Arab Emirates (UAE), along with Saudi Arabia, Bahrain and Egypt, cut diplomatic ties with Qatar on Monday.
According to earlier reports, Saudi Arabia accused Qatar of supporting "terrorism" and financing "groups" linked to Iran.
Announcing the decision on Monday to cut diplomatic relations with Qatar, Saudi Arabia also accused its fellow Gulf Arab state of interfering in its internal affairs.
Saudi Arabia was also cutting land, air and sea contact with Qatar, according to media reports.
Saudi Arabia's state news agency quoted an official source as saying that the move was to protect national security "from the dangers of terrorism and extremism."
Meanwhile in a statement carried by its official news agency, Bahrain accused Qatar of backing terrorism and interfering in Bahrain's internal affairs.
The UAE said in a statement it will "sever relations with Qatar, including diplomatic relations, and the country's diplomatic mission has a grace period of 48 hours to leave the country," UAE state news agency WAM reported.
Qatari nationals in the UAE would have 14 days to leave while Qatari nationals would be prevented from entering the UAE.
The UAE has taken these steps "as a result of the failure of the Qatari authorities" to stop funding "terrorist organizations ... especially the Muslim Brotherhood," it said.
The Brotherhood, which has been outlawed in Egypt, is labeled a terrorist organization in the UAE, Bahrain and Saudi Arabia.
The UAE also accused Qatar of "harboring extremists."
The UAE and Qatar are both members of the six-country Gulf Cooperation Council (GCC), to which Saudi Arabia and Bahrain also belong. Founded in 1981, the GCC is a leading political and economic block in the Arab world.
Egypt also announced its decision to cut diplomatic ties with Qatar earlier on Monday.
Egypt severed diplomatic ties with Qatar on accusations of supporting terrorist organizations, the Egyptian Foreign Ministry said in a statement.
"The Arab Republic of Egypt decided to cut diplomatic ties with Qatar in light of the Gulf Arab state's persistence to take a path against Egypt, and the failure of any attempts to prevent it from supporting terrorist organization, topped by the Muslim Brotherhood," said the statement.
The statement added Qatar is sheltering the leaders of the Brotherhood who have targeted the security and safety of Egypt by conducting terrorist operations.
The statement attributed cutting ties with Qatar to the state's promotion of extremist thoughts of al-Qaeda and Islamic State, its support for terrorist operations in Sinai, as well as its intervention in Egypt's internal affairs in a way that threatens its national security.
Ties between Egypt and Qatar have been deteriorating since the ouster of the Egyptian Islamist-affiliated leader Mohamed Morsi in 2013 as a result of a mass protest against his rule.
