Bas-Vully - Wondering where your package is? Look up!Switzerland's postal service said Tuesday it had begun testing parcel deliveries by unmanned drones, although widespread use of the flying postmen is not likely to kick in for another five years.Postal service executives showed off the drones for the first time Tuesday and said initial tests of the machines' post-delivery abilities would run until the end of July.The snow-white drones consist of four branches with propellers on the end extending from a hollow ring the size of a toilet seat. A yellow box, bearing the postal service logo, is lodged in the middle."The drone has an extremely light construction and is capable of transporting loads of up to one kilo over more than 10km with a single battery charge," Swiss Post said in a statement.The drone "flies autonomously, following clearly defined, secure flight paths, which are drawn up by cloud software developed by Matternet [the drone's US manufacturer]", Swiss Post added.Swiss Post, which is co-operating on the project with Swiss WorldCargo - the air freight division of Swiss International Air Lines -, stressed that the drones would be thoroughly tested before being put to wide-scale use."Until the time of their realistic commercial use in around five years, there are various requirements which need to be clarified," the statement said.This includes exploring the regulatory framework that would apply when sending the unmanned aircraft out across the Alpine country, which is dotted with numerous remote and isolated villages where drone deliveries could be useful.Swiss Post also said extensive tests would be carried out to explore the technical restrictions of the drones, including limited battery life.For now, Swiss Post said it expects to mainly use the drones in emergency situations, which could "involve bringing supplies to an area that has been cut off from the outside world following a storm." "Another realistic possibility is the urgent transport of consignments with the highest priority, such as laboratory tests," it added.Switzerland is not the only place where package-delivering drones could soon appear.Amazon, the world's largest online retailer, announced in late 2013 a plan to airlift small parcels to customers by drone in select markets, less than 30 minutes after an order is received.But the company warned last month that proposed US rules regulating the use of civilian drones could block it from launching the service, and called for them to be overhauled.