“Border facilities in all five districts — Chaghi, Washuk, Panjgur, Kech and Gwadar — have been suspended,” Qadir Bakhsh Pirkani, a senior official in Balochistan province, which borders Iran, told AFP.

Crossing into Iran “has been suspended until further notice”, said Atta ul Munim, an official at one of the crossings in Chaghi district.

However, there was “no ban on trade” activities at the border and Pakistani nationals needing to return to their country from Iran can cross, he added.

“We’re expecting around 200 Pakistani students coming today,” Atta said.

On Sunday, Pakistani Foreign Minister Ishaq Dar said 450 Pakistani pilgrims were evacuated from Iran, with more to follow, as well as from Iraq — the two countries hosting the holiest sites in Shiite Islam.

Pakistan, the only Muslim-majority country with nuclear weapons, said on Friday it “stands in solidarity with the Government and the people of Iran” against strikes by Israel, which both Islamabad and Tehran do not recognise.

Pakistani Defence Minister Khawaja Asif on Monday warned that the world “should be wary and apprehensive about Israel’s nuclear prowess” and accused it of lacking “any international nuclear discipline”.

Israel is the Middle East’s only nuclear power, although undeclared.

Media reports have said Pakistan may support Tehran if the conflict was to widen, but officials in Islamabad have reiterated that their country is only showing “moral and diplomatic solidarity”.

Predominantly Sunni Pakistan shares a more than 900-kilometre (560-mile) border with Shiite-majority Iran.

The relationship between the two neighbours has been complex, with Pakistan often wary of US-led sanctions on Tehran and also mindful of its ties with Riyadh, which has repeatedly helped rescue its economy by rolling over overdue debts.

Bilateral trade between the two countries stands at approximately $3 billion, and officials have pledged to increase it to $10 billion in the coming years.