Iran confirmed on Saturday that it has allowed the International Atomic Energy Agency to increase inspections of its nuclear programme.
"We have increased capacity – it is natural that the number of inspections should also increase," the official Irna news agency quoted the country's nuclear chief Mohammad Eslami as saying.
"When we carry out nuclear activities, and where we deal with nuclear materials, changing the scale will naturally change the monitoring level," he added.
An IAEA report earlier this week said Iran had agreed to tougher monitoring at its Fordow uranium enrichment plant south of Tehran.
The UN nuclear watchdog said that Iran had revamped Fordow so that it could "significantly increase the rate of production of uranium enriched up to 60 per cent", a short technical step from the 90 per cent enriched uranium needed to make a nuclear weapon.
Iran insists on its right to nuclear energy for peaceful purposes, and denies it is seeking an atomic weapons capability.
"The IAEA has always had access to monitor within the framework of the safeguard agreement and the NPT, and we have not created any obstacles for it and we will not do so," Mr Eslami said.
The Non-Proliferation Treaty or NPT requires member states to declare and maintain their nuclear materials under IAEA supervision.
Last month, Iran announced it would launch "new and advanced" centrifuges in response to an IAEA board resolution censuring Tehran for what it called a lack of co-operation with the agency.
Britain, France and Germany on Tuesday "condemned" Tehran's latest steps to expand its nuclear programme, "strongly urging" it to reverse them.
In a letter to the UN Security Council, the three European powers raised the possibility of restoring all UN sanctions against Iran to keep it from developing its nuclear programme.
Nuclear tensions with the West have soared since Donald Trump withdrew from a landmark 2015 deal with Tehran during his first term as US president. The deal, involving the US, Russia, China and the three European states, had provided sanctions relief in exchange for limits on Iran's nuclear programme.
Mr Trump has vowed to renew his campaign of “maximum pressure” on Iran when he returns to office in January.
With reporting from agencies.