* China data shows provinces had the sharpest Q1 slowdown
* Tight credit conditions in China restrain purchases
* Chart signals point lower for copper
(Adds details, quotes, updates prices)
LONDON, April 29 (Reuters) - Copper dipped on Tuesday as investors held back ahead of a U.S. central bank meeting and after further signs of slower growth in top metals consumer China.
Three-month copper on the London Metal Exchange fell 0.3 percent to $6,727.75 a tonne by 1510 GMT after touching a peak of $6,798 a tonne on Monday, its highest level since March 7.
Investors expect U.S. Federal Reserve policymakers on Wednesday to continue paring their massive bond-buying stimulus in the world's largest economy.
"Another ... tapering announcement could be bullish for the dollar but bearish for copper," Naeem Aslam, chief market analyst at Ava Trade in Dublin, said.
A stronger dollar makes commodities priced in the U.S. currency more expensive for holders of other currencies and typically puts pressure on prices.
"But it is important not to underestimate the fact that the Fed are only tapering because they believe the economy is becoming stronger and this is a positive influence for copper in the long run," Aslam added.
This argument, he said, would be cemented if U.S. payroll data due on Friday beats market expectations. Copper is used extensively in construction and wiring, and an improving economy could mean more building.
Trading was quiet ahead of holidays in Asia this week and next Monday in Britain.
Concern about growth in China, which accounts for about 40 percent of global copper demand, continued to bubble after official data showed China's resource-dependent and manufacturing-heavy provinces suffered the sharpest economic slowdown in the first quarter.
Copper prices have risen nearly 2 percent so far in April, helped by tight credit conditions in China that have restricted some copper consumers' access to bonded stocks in Shanghai.
Chart signals for copper were pointing lower, independent technical analyst Cliff Green said.
"The recovery over the past few weeks appears purely corrective in structure and looks to be running out of steam," he told the Reuters Global Base Metals Forum. "Expect resistances waiting at $6,800, then $6,900 to turn values lower once again."
Nickel, the top performer in the base metals complex, slipped as investors started closing their positions after gains of 30 percent since an Indonesian ban on unprocessed ore exports in January.
LME benchmark nickel shed 0.9 percent to $18,010 per tonne. It hit an intraday peak of $18,715 on Monday, its highest level in almost 15 months, but some analysts say prices will struggle to go much higher.
Nickel also lost steam after the latest list of Russian companies targeted for sanctions by the United States did not include metals companies such as top refined nickel producer Norilsk Nickel.
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
Three month LME tin
(Additional reporting by Melanie Burton in Sydney; Editing by William Hardy and Jane Baird)