"The infectious virus is now spreading all across Portugal, and in particular in Portugal's northern region, where is Braga is located," Rio said in a letter to Jiang Youwei, mayor of Shenyang. "We are now in lockdown, and only essential services are working. We are facing an unprecedented humanitarian and health crisis."

He added: "China demonstrated strong leadership in this crisis, and the way your country is resolving this pandemic is an example to the world, and particularly to us in Portugal. Based on the friendly relations between Braga and Shenyang, I would ask for your help."