The Arab world's strongest powers cut ties with Qatar on Monday over alleged support for Islamists and Iran, re-opening a festering wound two weeks after U.S. President Donald Trump's demand for Muslim states to fight terrorism.

Saudi Arabia, Egypt, United Arab Emirates and Bahrain cut relations with Qatar in a coordinated move. Yemen, Libya's eastern-based government and the Maldives joined in later.

Qatar denounced the move as based on lies about it supporting militants. It has often been accused of being a funding source for Islamists, as has Saudi Arabia.

Iran, long at odds with Saudi Arabia and a behind-the-scenes target of the move, blamed Trump's visit last month to Riyadh.

"What is happening is the preliminary result of the sword dance," Hamid Aboutalebi, deputy chief of staff of Iran's President Hassan Rouhani, tweeted in reference to Trump's joining in a traditional dance with the Saudi king at the meeting.

The diplomatic broadside threatens the international prestige of Qatar, home to a large U.S. military base and set to host the 2022 World Cup.

The hawkish tone Trump brought in his visit to over 50 Muslim leaders in Riyadh on Tehran and on terrorism is seen to have laid the groundwork for the diplomatic crisis. It was unclear how it would play with the military base.

"You have a shift in the balance of power in the Gulf now because of the new presidency: Trump is strongly opposed to political Islam and Iran," said Jean-Marc Rickli, head of global risk and resilience at the Geneva Centre for Security Policy.

"He is totally aligned with Abu Dhabi and Riyadh, who also want no compromise with either Iran or the political Islam promoted by the Muslim Brotherhood."

Qatar has for years presented itself as a mediator and power broker for the region's many disputes, but Egypt and the Gulf Arab states resent Qatar's support for Islamists, especially the Muslim Brotherhood, which they see as a political foe.

Closing all transport ties with Qatar, the three Gulf states gave Qatari visitors and residents two weeks to leave.

In the harshest measures, Saudi Arabia and Bahrain's civil aviation bodies banned Qatari planes from landing in the kingdom's airports and banned them from crossing their airspace.

Saudi Arabia accused Qatar of backing militant groups and broadcasting their ideology, an apparent reference to Qatar's influential state-owned satellite channel al Jazeera.

"(Qatar) embraces multiple terrorist and sectarian groups aimed at disturbing stability in the region, including the Muslim Brotherhood, ISIS (Islamic State) and al-Qaeda," Saudi state news agency SPA said.

It accused Qatar of supporting what it described as Iranian-backed militants in its restive and largely Shi'ite Muslim-populated Eastern region of Qatif and in Bahrain. Qatar was also expelled from the Saudi-led coalition fighting a war in Yemen.

Qatar denied it was interfering in the affairs of others.

"The campaign of incitement is based on lies that had reached the level of complete fabrications," the Qatari foreign ministry said in a statement.