Copper prices stabilised close to 4-year lows on Friday as disruption to supply caused by shutdowns of mines and shipping routes began to offset the huge hit to demand from the coronavirus outbreak. Benchmark copper was down 0.2% at $4,795 a tonne at 1700 GMT on Friday and roughly unchanged this week. The metal used in power and construction last week saw its biggest weekly loss since 2011 - down 11% - and touched $4,371, the lowest since January 2016. Prices have fallen more than 20% so far in 2020. South Africa closed its ports on Thursday, disrupting shipments from countries that produce a tenth of global copper supply, while Glencore became the latest in a long list of companies to suspend or slow mining operations. Coronavirus is spreading rapidly in the United States and Europe, shutting down large parts of the economy, but China is slowly returning to work. Chilean copper miner Codelco said output had dropped 5.3% in 2019 to 1.59 million tonnes.