Iran must "seriously improve" cooperation with the United Nations inspectors to avoid heightening tensions with the West, the Financial Times reported on Wednesday, citing International Atomic Energy Agency chief Rafael Grossi.

Grossi told the FT that while the IAEA has carried out about a dozen inspections in Iran since the war imposed by Israel in June, it had not been given access to nuclear facilities such as Fordow, Natanz and Isfahan, which were bombed by the United States.

Grossi claimed in October that movement had been detected near Iran's enriched uranium stockpile but that it did "not imply that there is activity on enrichment".

Iranian Foreign Ministry spokesperson Esmaeil Baghaei subsequently said that Grossi was "fully aware of the peaceful nature" of Iran's nuclear programme and should not express "unfounded opinions" on it.

Iranian officials have blamed the IAEA for providing a justification for Israel's bombing, which began the day after the IAEA board voted to declare Iran in violation of obligations under the Nuclear Non-Proliferation Treaty.

Grossi told the FT that while the agency was trying to approach the "bumpy" relations with Iran with understanding, the country still needed to comply.

On June 13, Israel launched a blatant and unprovoked aggression against Iran, triggering a 12-day war that killed at least 1,064 people in the country, including military commanders, nuclear scientists, and ordinary civilians.

The United States also entered the war by bombing three Iranian nuclear sites in a grave violation of international law.

In response, the Iranian Armed Forces targeted strategic sites across the occupied territories as well as the Al-Udeid air base in Qatar, the largest American military base in West Asia.

On June 24, Iran, through its successful retaliatory operations against both the Israeli regime and the US, managed to impose a halt to the aggression.