* Copper heads for second straight weekly drop
* Demand doubts counter supply pinch in Chile, Indonesia
* GRAPHIC-2017 metal returns: tmsnrt.rs/2eqHKkL (Updates with closing prices, adds comment)
By Jan Harvey
LONDON, Feb 24 (Reuters) - Copper clawed back some of the previous session's hefty losses on Friday as supply disruptions in Chile and Indonesia lent support, but still posted a second straight weekly drop as concerns over the demand outlook weighed.
The metal used in construction fell 3 percent on Thursday, its biggest one-day drop in 17 months, as traders flagged persistent worries over Chinese consumption.
Some investors also cashed in after copper hit a 21-month high of $6,204 on Feb. 13 on supply outages from major copper mines and hopes a pledge by the administration of U.S. President Donald Trump to lift infrastructure spending would fuel demand.
The metal remained well off its February peak on Friday.
Three-month copper on the London Metal Exchange closed at $5,928 a tonne, up 1.2 percent from the previous day but still half a percent lower on the week.
"All the signs coming out of China are that the authorities are committed to reining in credit growth this year, rather than stimulating economic growth at all costs. That would be negative for copper," Capital Economics analyst Caroline Bain said.
"Yes, there are supply disruptions, but stocks are also very high," she added. "Copper started to rally after Trump got elected in the U.S. There was optimism there about demand, given his fiscal stimulus plans ... We think again there'll be disappointment about demand on that front."
China's refined copper imports fell 14 percent last month, Chinese customs data showed on Friday.
Strike action at the Escondida copper mine in Chile, which accounts for about 6 percent of world supply, and a halt to the Grasberg copper mine in Indonesia by Freeport McMoRan, gave copper bulls solace, however.
Nickel saw the day's biggest gains, closing up 2.6 percent at $10,860 a tonne.
"Nickel's year to date 11.3 percent increase in price has been spurred by substantial mine closures in the Philippines and the expectation of increased demand from the U.S. and China," Natixis said in a note.
"Chinese nickel demand is expected to increase in 2017 due to a rise in steel manufacturers moving into higher value-added stainless steel products."
Zinc ended the day 1.4 percent higher at $2,829 a tonne. Zinc prices are nearly double the levels seen in January 2016 due to deficits arising from mine closures and shutdowns.
Tin closed 2 percent higher at $19,150 a tonne, and lead up 1 percent at $2,260 a tonne. Aluminium closed up 1 percent at $1,885 a tonne.
Three month LME copper
Most active ShFE copper
Three month LME aluminium
Most active ShFE aluminium
Three month LME zinc
Most active ShFE zinc
Three month LME lead
Most active ShFE lead
Three month LME nickel
Most active ShFE nickel
Three month LME tin
Most active ShFE tin
Additional reporting by James Regan in Sydney; Editing by Alexander Smith and Elaine Hardcastle