Iran has the capacity to start enriching uranium again - for a possible bomb - in "a matter of months", the head of the UN's nuclear watchdog has said.

According to BBC, Rafael Grossi, head of the International Atomic Energy Agency (IAEA) told CBS News, that Tehran could have "in a matter of months... a few cascades of centrifuges spinning and producing enriched uranium".

He added that Iran still possessed the "industrial and technological capacities... so if they so wish, they will be able to start doing this again."

Grossi said the US strikes on three Iranian sites last weekend had caused severe but "not total" damage, contradicting Donald Trump's claim that Iran's nuclear facilities were "totally obliterated".

The IAEA is not the first body to suggest that Iran's nuclear abilities could still continue - earlier this week, a leaked preliminary Pentagon assessment found the US strikes probably only set the programme back by months.

Israel attacked nuclear and military sites in Iran on June 13, claiming Iran was close to building a nuclear weapon. The US later joined the strikes, dropping bombs on three of Iran's nuclear facilities: Fordo, Natanz and Isfahan. Since then, the true extent of the damage has been unclear.

It is possible, however, that future intelligence reports will include more information showing a different level of damage to the facilities.

71 killed in Israeli strike on Evin prison, says Tehran

At least 71 people were killed in Israel's attack on Tehran's Evin prison, a notorious facility where many political prisoners and dissidents have been held, Iran's judiciary said on Sunday.

Judiciary spokesperson Asghar Jahangir posted on the office's official Mizan news agency website that those killed on Monday included staff, soldiers, prisoners and members of visiting families. It was not possible to independently verify the claim. 

The June 23 attack, the day before the ceasefire between Israel and Iran took hold, hit several prison buildings and prompted concerns from rights groups about the safety of the inmates.

Jahangir did not break down the casualty figures but said the attack had hit the prison's infirmary, engineering building, judicial affairs and visitation hall.