* Tin at 20-month high on falling inventories
* Nickle hit by potential Philippines mine closures
* Copper gains 0.5 pct to close at $4,842 (Updates with closing prices)
By Clara Denina
LONDON, Sept 29 (Reuters) - Lead climbed on Thursday to its highest since May last year, supported by steadier copper prices and worries over mine supply, while nickel retreated from a seven-week high.
Three-month lead on the London Metal Exchange CMPB3 closed up 3.3 percent at $2,062.50 a tonne. The metal hit $2,070.50 earlier, its strongest since May 2015, extending gains from the previous session, when rising oil prices also lent support. O/R mine shutdowns over the past year and moves by lead producers to curb output in the face of low prices have tightened global supplies of the metal used to make batteries.
"Lead, which had underperformed the other base metals for much of this year, has been catching up in the past couple of months ... with contraction in lead mine supply and refined lead," said Caroline Bain, senior commodities economist at Capital Economics.
On the Shanghai Futures Exchange, the lead contract for November delivery SPBcv1 closed up 2.2 percent at 15,005 yuan ($2,250) a tonne.
China's imports of lead ore and concentrate dropped 10 percent in the first eight months of the year.
The metal was supported by a steadier copper CMCU3 price, which closed 0.5 percent higher at $4,842 a tonne. More widely traded copper is usually seen as a benchmark for other metals.
A power outage in South Australia state has halted 300,000 tonnes of annual copper production capacity from BHP Billiton's BHP.AX BLT.L Olympic Dam and Oz Minerals' OZL.AX Prominent Hill mines. three-month tin CMSN3 climbed above $20,000 a tonne for the first time in 20 months and was bid at $20,025 at the close. LME tin inventories have dropped by more than 50 percent over the past four months.
Aluminium CMAL3 closed 0.4 percent higher at $1,671, while zinc CMZN3 was up 1 percent at $2,356.
Nickel CMNI3 bucked the uptrend across the complex, retreating from Tuesday's seven-week top of $10,900 a tonne, when the Philippines said it might suspend 20 more mines for environmental infractions. Philippines, the world's biggest nickel ore supplier, has already halted 10 mines, eight of them nickel producers.
Prices closed with a 2.4 percent decline at $10,435.
"For nickel, obviously the market is tightening and obviously these closures will mean that in six to nine months down the road refineries could be struggling to find ore," Capital Economics' Bain said.
"But the bigger picture remains one of really quite high stocks, so physical tightness is the market is still some time off."
Shanghai nickel SNIcv1 ended 0.3 percent lower at 81,860 yuan a tonne after touching a seven-week high of 83,610 yuan.
Macquarie said in a note that disruption from the Philippines to the global market could be capped at between 15,000 to 20,000 tonnes of nickel ore, given the upcoming monsoon season which limits mining and shipments. Macquarie sees global nickel supply at 1.9 million tonnes this year.
PRICES
Three month LME copper
CMCU3
Most active ShFE copper
SCFcv1
Three month LME aluminium
CMAL3
Most active ShFE aluminium
SAFcv1
Three month LME zinc
CMZN3
Most active ShFE zinc
SZNcv1
Three month LME lead
CMPB3
Most active ShFE lead
SPBcv1
Three month LME nickel
CMNI3
Most active ShFE nickel
SNIcv1
Three month LME tin
CMSN3
Most active ShFE tin
SSNcv1
($1 = 6.6705 Chinese yuan)