The US vice-president, ⁠JD Vance, has said a number of issues still need to be figured out with Iran, as many Republicans expressed scepticism of the agreement reached this week by Donald Trump, and pressed the White House to release more information about it.

The memorandum of understanding (MOU) announced Sunday to end the war in Iran, set for a ceremonial signing on Friday in Geneva, is centred around reopening the strait of Hormuz and lifting the United States’ naval blockade in the region, along with financial incentives for Iran if it meets certain benchmarks.

In an interview with CNN on Monday, Vance called it “a very general document” with specifics ⁠of the ​deal ‌to be ‌worked out during further ‌negotiations.

“The MOU … is about a page,” Vance ​said. “On a number of ​issues, ​we are ​going to ​have ‌to figure ​this ​stuff out during the technical negotiation phase.”

His comments came as many Senate Republicans who returned to Washington on Monday said there were still many unanswered questions about the deal and they need thorough briefings before it was finalised.

“I just don’t know enough about it,” Republican John Thune told reporters in the Capitol. “Even the people who follow this stuff closely up here don’t know that much about it.”

Congressional leaders and intelligence committees generally receive higher-level intelligence briefings before rank-and-file members, and they are notified of major developments before they are announced. But Thune, who is the Senate majority leader, said he had not been personally briefed on the deal.

“I think that my understanding of what it entails – and, again, not having seen anything … I think the issues are going to be compliance, and how are you going to enforce that,” Thune said.

Thune’s concerns were echoed by several other Republican senators.

“If it’s a secret deal then how can I take it seriously?” asked Thom Tillis of North Carolina.

Trump has not yet explained how his agreement will address Iran’s nuclear program, including who will be in charge of verifying that Iran is in compliance and who will destroy or remove highly enriched uranium believed to be buried under nuclear sites that were badly damaged by US strikes last summer.

The memorandum of understanding also includes the possibility of releasing Iran’s frozen funds, sanctions relief and a $300bn fund to help rebuild Iran if Tehran meets certain benchmarks, US officials told reporters on Monday. But the document has not been released.

Thune said he wants to know more about the conditions on the financial incentives for Iran. He said the deal would be a “good one” if the incentives are conditioned upon Iran winding down its nuclear program and getting rid of the enriched uranium, “preventing them from having a nuclear capability in the future”.

In interviews on Monday, Vance appeared to confirm that the $300bn reconstruction fund was in the agreement, but noted that it would be paid for by neighbouring Gulf states.

Vance said that the White House would release the text this week, “and what everybody will see is that Iran doesn’t get a dime of money unless they perform their obligations”.

Iran agreed to sharply curtail its nuclear program in a deal signed in 2015 with the Obama administration. Trump withdrew the US from that accord during his first term as president. That agreement allowed Iran to regain billions of dollars in frozen assets, which Trump has frequently derided as sending “pallets of cash” to Iran.

Senator Lindsey Graham, a close ally of Trump and a longtime hawk on Iran, expressed scepticism over the emerging agreement, saying he wants to see the memorandum that the two countries have agreed on, and Congress will need to review and vote on it.

“The way Iran describes it, it’s awful. The way we describe it, it makes sense to me,” Graham said. “Let’s look at it and see what it actually is.”

Vance responded to Graham on Monday, saying in an interview with ABC that he would “caution Lindsey Graham and anybody else not to believe the hardliner propaganda in Iran, but to believe what’s actually in the agreement.”

With the Associated Press