The deputy head of Iran's Atomic Energy Organisation, Muhammad Saeedi, said Tehran wanted to temporarily remove UN seals at some parts of the Isfahan uranium conversion facility despite its agreement with Britain, France and Germany.
"We have asked the IAEA to let us remove the seal at some parts of the facility in the presence of the visiting IAEA inspectors.
"We want to test equipment there to check whether those are functional. It does not mean lifting the suspension," he said.
Diplomats from the three big EU countries have long said testing of machinery used in the nuclear fuel cycle should be frozen under the November suspension agreement signed in Paris.
A diplomat from one of the EU trio said it was unclear how they would react.
"We want to test equipment there to check whether those are functional. It does not mean lifting the suspension"
Deputy head, Iran's Atomic Energy Organisation
"The odds are that we will see this as a maintenance operation that does not amount to a significant breach of the Paris Agreement," the diplomat said.
However, the United States fears Iran is using its nuclear energy programme as a front to develop nuclear weapons and have called on Iran to cease all sensitive atomic work.
Washington made it clear it would not tolerate even a small breach of the Paris Agreement.
"Any contravention of the Paris agreement would be a step backwards, not a step forward," US State Department spokesman Sean McCormack said in Washington.
McCormack underscored the US position that Iran should not resume enrichment-related activities.
"We've made very clear ... that conversion and enrichment activities would not be allowed under the Paris Agreement and are specifically forbidden by it," he said.
EU diplomats plan to offer Iran
incentives not to go nuclear
Meanwhile, the EU trio has promised to give Iran a comprehensive offer of incentives by the end of July or the beginning of August.
In exchange, Brussels called for "objective guarantees" that Tehran's nuclear programme was for peaceful purposes only.
The Europeans say this can only be a permanent cessation of all enrichment-related work, including the Isfahan plant, which prepares raw uranium for enrichment.
Tehran says its programme is peaceful and refuses to give up its sovereign right to a full atomic programme.