Saudi Arabia and its Gulf allies have sanctioned a dozen organisations and 59 people it accuses of links to Islamist militancy - a number of them Qataris or with links to Qatar - escalating the diplomatic crisis in the region.
Launching an extraordinary allegation against a key USA military partner, Trump derided what he called Qatar's "extremist ideology in terms of funding" terrorist groups, an accusation Qatar has repeatedly and vehemently denied.
The Pentagon said it agreed with Mr Tillerson's analysis of the impact of the blockade.
- Doha dismisses the "terror finance watch list" by the four Arab nations as "baseless". "This is a foreign policy that has gone wild", state minister for foreign affairs Anwar Gargash told AFP. "Qatar and its big rivals are fighting each other, but indirectly and on other people's territory", said Yemeni analyst Farea al-Muslimi.
Amnesty also pointed out that Bahrain, Saudi Arabia and the UAE had warned of harsh punishments, including up to 15 years in jail, "if they dare to criticize these measures" against Qatar. He also mentions that Iran has pledged to help Qatar with food and three of Iran's ports will be designated for Qatar.
In a wide-ranging interview with The Associated Press, Qatari Foreign Minister Sheikh Mohammed bin Abdulrahman Al Thani repeatedly denied that his country funded extremists and he rejected the idea of shutting down its Al-Jazeera satellite news network.
The Saudi Press Agency on Monday accused Qatari officials of repeatedly violating "their global obligations and the agreements they signed under the umbrella of the Gulf Cooperation Council for Arab States to cease hostilities against [Saudi Arabia] and stand against terrorist activities". His wife is a UAE national and is forbidden from travelling to Qatar, while his children are Qatari nationals and so are required to leave the UAE. It hosts the forward headquarters of the US military's central command in the region. "They need to make a decision; they can't have it both ways", he said. In the call, the president, "offered to help the parties resolve their differences, including through a meeting at the White House if necessary", the White House said.
On Saturday, Turkish Foreign Minister Mevlut Cavusoglu said his country hoped the rift between the "Muslim countries" would end "through peaceful dialogue before the religious holiday", referring to Eid al-Fitr which marks the end of Ramadan. "We are a platform for peace", he told reporters in Doha in a defiant tone.
According to Sky Italy, supporters caught donning shirts with the Qatar Airways logo now face €135,000 fines (around £120,000) and up to 15 years in jail. "This litany of subversive support, infringement, actions is huge but I would say the most serious is the extremists and terrorist angle", Gargash said.
For its part, Qatar issued an overnight statement saying residents living in the country from those nations that severed ties would have "complete freedom" to stay despite the "hostile and tendentious campaigns" now targeting it.
"We call on Qatar to be responsive to the concerns of its neighbors", he said.
- Abu Dhabi port eases restrictions on oil tankers going to and from Qatar.
Up to 5,000 Turkish soldiers might be deployed to Qatar under the new legislation, Rudaw news reports, adding that the troops are now on standby and ready for their deployment.
Many economists at financial institutions in the Gulf decline to discuss Qatar publicly because of the political tensions, but privately they say they expect Qatar to defend itscurrency successfully.
Saudi Arabia said an immediate change of policy by Qatar was essential.
"The emir is wise not to speak", said Faraj, a Qatari engineer working for a telecommunications company. Yesterday, Emirati officials shut down the airline's offices in the UAE.
Saudi Arabia and its allies today welcomed an accusation by President Donald Trump that Qatar was bankrolling extremism but ignored a separate United States call for them to ease their economic blockade.
"The nation of Qatar, unfortunately, has historically been a funder of terrorism at a very high level", Trump said, echoing an allegation the Saudi-led group has used to justify cutting diplomatic ties to the tiny gas-rich kingdom. Saudi Arabia, however, is locked in a regional power struggle with Iran. Since the 2011 "Arab Spring" protests, which aspired to democratic reform but in several countries collapsed into warfare, Egypt and especially the United Arab Emirates emerged as main foes of an ascendant Muslim Brotherhood backed by Qatar.
At a news conference earlier, he called the actions by the Gulf states "a clear breach of worldwide law".
Egypt and Bahrain cut travel and diplomatic ties with Qatar on Monday.