LME three-month copper closed up $90 at $8110 per tonne. The red metal is remaining firm on the back of supply threats with Southern Copper union workers in Peru set to begin indefinite strike action. The bulk of copper plays on the Final Call watch list also made gains today with Oxiana closing up 2c at $3.94, Straits Resources adding 9c to close at $4.89, and CopperCo climbing 7c to close at $1.225.