The Republican chairman of the Senate foreign relations committee has said the US Congress will hold up approval of arms sales to the Gulf as a result of the Saudi-led blockade of Qatar.

Senator Bob Corker said the nations of Gulf Cooperation Council had failed to take advantage of a summit with President Trump in May to overcome their differences and had “instead chosen to devolve into conflict”.

Corker continued: “For these reasons, before we provide any further clearances during the informal review period on sales of lethal military equipment to the GCC states, we need a better understanding of the path to resolve the current dispute and reunify the GCC.”

Earlier this month, the Senate narrowly fended off a bid to block a Trump administration plan to sell Saudi Arabia $500m in precision-guided munitions, part of a proposed $110bn arms sales package announced during the president’s visit to Riyadh last month.

Congress has the power to block individual sales during a 30-day review period from when the state department gives notification of an impending sale.

A Saudi-led coalition that includes Egypt, the United Arab Emirates and Bahrain cut ties with Qatar on 5 June, but only provided a justification 18 days later with the presentation of a list of 13 demands.

They want Doha to close the al-Jazeera TV channel, restrict diplomatic ties with Iran, halt the construction of a Turkish military base in the country, and sever contacts with extremist organisations. Qatar has been given 10 days to meet the demands, but the Saudi-led group has not said what action it would take if the deadline is not met.

The US has sent mixed signals on the standoff. In the immediate aftermath of the embargo, Trump gave Riyadh and its allies fulsome support, echoing Saudi claims about Qatari funding for terrorism.

However, Rex Tillerson, the secretary of state, last week called on the coalition present its complaints and negotiate a solution. Since the list of 13 demands was presented, Tillerson has been non-committal, observing that some of them would be “very difficult for Qatar to meet”, but arguing there were “significant areas which provide a basis for ongoing dialogue leading to resolution.”

The German foreign minister Sigmar Gabriel likened the crisis to an Arabic House of Cards, adding the demands being made of Qatar were provocative. He also said Qatar was by no means the only country in the region responsible for funding terrorism, and added Europe had to do more to influence US thinking in the Middle East.

“It falls on us Europeans to convince the US to continue supporting the international system,” Gabriel said at a speech given to the European Council on Foreign Relations.

Speaking at the same event, the Iranian foreign minister Zarif said the countries who blamed Iran or Qatar for terrorism were trying to avoid taking responsibility for their own failures in addressing the demands of their own people.

“One day it’s Iran, today it’s Qatar,” he said. “It’s an attempt to evade responsibility, escape accountability for this very fundamental … failure of the state system to address, to respond to the demands of its populus.”

Zarif argued for a new regional dialogue forum for the Gulf countries and called for an end to the armaments spiral in the region, which he said influenced some western countries’ relations with states in the region.

“When foreign policy becomes a commodity, then purchasing military equipment becomes your yardstick for measuring who is a terrorist or who isn’t a terrorist,” he said.

“This reinforces a cognitive disorder in our region that security can be purchased from outside, that security can be purchased by trying to buy more military equipment,” he added. “What is needed in our region is a regional dialogue forum.”