Vienna  - Iran will not work with the International Atomic Energy Agency (IAEA) to clear up allegations of past nuclear weapons studies unless the agency treats its work in Iran as a routine matter, Tehran's UN ambassador in Vienna said Tuesday.

Although Tehran has answered questions that both sides agreed to in a work plan last summer, IAEA Director General Mohamed ElBaradei said in his latest Iran report that no substantive progress had been made to clear up remaining issues concerning studies that seem to have been related to nuclear weapons.

"The issue of alleged studies is over, the work plan is over and this endless process should be put to an end," Iranian Ambassador Ali Asghar Soltanieh told reporters after an IAEA briefing on the Iran report for diplomats.

However, if the agency's monitoring of Iran's nuclear programme were to become "routine", Iran was prepared to answer further questions, the diplomat said.

Currently, the IAEA is investigating Iran not only on behalf of its 35-member board of governors, but also under resolutions of the United Nations Security Council, which has passed three rounds of sanctions against Tehran.

In his latest report, ElBaradei wrote that the IAEA had documents indicating that there were administrative and technical links between past Iranian work on uranium conversion, explosives testing, and missile development, all of which appear to be related to nuclear weapons.

In the IAEA briefing, diplomats were shown photographs and documents indicating that Iran might have redesigned the warhead of a Shahab-3 missile to carry a nuclear warhead, the US ambassador to the IAEA, Gregory Schulte, said.

Iran, which denies the allegations, is criticizing the US for not allowing the IAEA to show Tehran original documents obtained from several intelligence agencies.

Soltanieh also said the investigation intruded into his country's military secrets. "No country in the world will give information about its military conventional activities," he said.

The IAEA board will meet from next Monday to discuss the latest report, which also stated that uranium enrichment was continuing in Iran, despite the UN Security Council's demands to stop it.

White House spokeswoman Dana Perino said Monday that Iran risked further isolation and possible sanctions for failing to comply with the IAEA.

But she conceded that it could be more difficult to strengthen sanctions because of tension with Russia over the invasion of Georgia. Moscow holds veto authority on the UN Security Council. (dpa)