* LME/ShFE arb: http://tmsnrt.rs/2oQ5nm2
* Chinese zinc imports rise 21 pct in April, copper down 41 pct
* Chinese exports of aluminium semis up 8 pct (Updates with closing prices)
LONDON, May 23 (Reuters) - Zinc hit a three-week peak on Tuesday after imports of the metal into top consumer China rose, underlining potential shortages, but copper was under pressure on indications of healthy supply.
Imports of refined zinc to China increased 21 percent in April to 47,469 tonnes year-on-year while shipments of ore and concentrates jumped 44 percent, customs data showed.
Industry sources said that China is stepping up imports as dwindling global supplies of concentrate following mine closures hit local output of the metal, used to galvanise steel.
"Those import numbers showing that China's importing more in April could be evidence showing things are tightening up in China, which is the biggest consumer," said Robin Bhar, head of metals research at Societe Generale.
Copper imports in China, however, fell 41 percent, partly due to tighter credit.
"That reflects that the import arb (arbitrage) was essentially closed in the first quarter and has only fleetingly been opened from time to time," Bhar added.
* ZINC: London Metal Exchange benchmark zinc closed up 1 percent at $2,658 a tonne after touching $2,669, the highest since May 2.
* COPPER: LME three-month copper ended 0.2 percent lower at $5,714 after dipping to an intraday low of $5,666.
* COPPER SURPLUS: The global world refined copper market showed a 93,000 tonnes surplus in February, compared with a 55,000 tonnes surplus in January, the International Copper Study Group (ICSG) said in its latest monthly bulletin.
* LEAD: LME lead rose 0.2 percent to end at $2,069.
* LEAD STOCKS: On-warrant LME lead stocks, those not earmarked for delivery, jumped by a quarter and nearby tightness in lead spreads dissolved. The cash over the three-month contract flipped to a $23.25 discount, the widest since July 2014, after having been at a $34.50 premium in late April. <CMPB0-3>
* ALUMINIUM: LME aluminium shed 0.3 percent to finish at $1,943 after Chinese exports of semi-finished products rose 8.1 percent in April to 380,000 tonnes.
"China April exports rose ... in further signs that the much discussed potential capacity cuts are yet to take hold," Alastair Munro at broker Marex Spectron said in a note.
* NICKEL - The LME price retreated 0.5 percent to close at $9,345 after Chinese ore imports surged 48 percent. "Recovering ore exports from the Philippines were responsible for the bulk the April rebound," Trace Xian Liao at Citi said in a note.
* TIN prices finished up 0.1 percent at $20,500.
(Editing by Ed Osmond and David Evans)