Vienna: The UN nuclear agency said on Friday that its attempts to probe allegations that Tehran worked on nuclear weapons were deadlocked — a finding that all but rules out hopes of full nuclear deal between six world powers and Iran by the November 24 target.

Iran agreed in February to work with the International Atomic Energy Agency (IAEA), in what was seen as a test of Tehran’s professed new willingness to reduce tensions over its nuclear programme.

Since then, the agency has sought information on alleged experiments with detonators that can be used to set off nuclear explosions” work on high-explosive charges used in nuclear blasts, and alleged studies on calculating nuclear explosive yields.

Iran denies wanting — or ever working on — nuclear arms. Since February, it has provided information only on the detonators, insisting that they were used for oil exploration or non-nuclear military purposes. The agency says interconnected information suggests that they were being tested for nuclear weapons use.

“Iran has not provided any explanations that enable the agency to clarify the outstanding practical measures,” said the confidential report from the IAEA.

The finding is significant in recording where the investigation stands for the US and five other world powers negotiating with Iran.

The US and its allies say no final agreement will be reached until the IAEA says it’s satisfied with its inquiry.

With the IAEA investigation stalled, the agency has little hope of reaching final conclusions by November 24.

Diplomats have said that — if agreement is reached constraining Iran’s uranium enrichment programme and other activities that could be turned to making nuclear arms — Washington was willing to extend the IAEA investigation.

That would likely be opposed by hardliners in Tehran and US congressional critics, particularly after this week’s Republican sweep of Congress.