"We have decided not to take a chance and keep all of them under observation for the next 15 days," Najeebullah Qambrani, assistant commissioner at the Taftan border crossing, told AFP, saying 250 people were being quarantined.
Balochistan's secretary of health Mudassir Malik confirmed the quarantine but estimated that between 200 and 250 were being held.
He added that around 7,000 pilgrims had returned to Pakistan from Iran this month alone. Afghanistan and Pakistan share long, porous borders with Iran that are often used by smugglers and human traffickers, while millions of Afghan refugees currently live in the Islamic Republic - raising fears that the virus could easily spread over the border. Pakistan - bordered by China to the north and Iran to the south - also suffers the additional burden of having a lacklustre healthcare system following decades of under-investment by the state, leaving impoverished, rural communities especially vulnerable.