* Asian stock markets: tmsnrt.rs/2zpUAr4
* Investors question speed of stock rally
* China shares eye chance of stimulus
* Oil prices extend gains in Asia
By Stanley White and Chris Prentice
TOKYO/WASHINGTON, May 21 (Reuters) - Asian shares stepped back slightly and U.S. stock futures fell on Thursday as lingering caution about the long-term impact of the coronavirus outbreak offset some of this week's enthusiasm over re-opening of economies.
Investors were also looking ahead to a key policy gathering in China that may yield more economic stimulus, while recent data around the world underscored that a sustainable recovery is several months away.
MSCI's broadest index of Asia-Pacific shares outside Japan was up just 0.04%, having rallied around 3% so far this week. S&P 500 e-mini stock futures fell 0.66%. Broad risk appetite has been checked somewhat by escalating tensions between the United States and China due to President Donald Trump's criticism of Beijing's handling of the coronavirus outbreak.
Australian shares, which have been hampered by concerns about a trade row with China, pulled back slightly from a two-month high.
Japan's Nikkei stock index slid 0.05% after data showed the country's exports collapsed in April.
Shares in China fluctuated between gains and losses before the start of the annual parliament meeting on Friday.
The focus will be on Premier Li Keqiang's 2020 work report on the opening day of the National People's Congress (NPC), where he is expected to announce key economic targets and details on fiscal stimulus plans.
Global equities were buoyed this week as governments around the world gradually loosened their coronavirus lockdown restrictions, but many investors remain wary of the outlook as a raft of recent data suggested a full-blown recovery is likely some way off.
"Equities are still in an uptrend, but the pace of the rebound has been a little quick and we are running into resistance," said Kiyoshi Ishigane, chief fund manager at Mitsubishi UFJ Kokusai Asset Management Co in Tokyo.
"The (global) services sector has been decimated. The level of unemployed suggests this recovery will take some time."
On Wall Street, the S&P 500 gained 1.67% on Wednesday, but the positive mood did not last long in Asia.
U.S. crude ticked up 0.45% to $33.64 a barrel, while Brent crude rose 0.64% to $35.98 per barrel in a sign of easing concerns about a supply glut.
The dollar edged higher to $1.0964 per euro and rose to $1.2202 against the British pound.
The greenback also gained against the Australian and New Zealand dollars in a sign that some investors remain averse to risk.
Minutes from the U.S. Federal Reserve's April meeting released on Wednesday showed policymakers reaffirmed a pledge to keep interest rates near zero until they are confident the economy is on track to recovery.
The U.S. government auctioned $20 billion of 20-year debt on Wednesday for the first time since 1986. The 20-year yield eased slightly to 1.1602% in Asia, while the yield on benchmark 10-year Treasury notes fell to 0.6639% as traders sought the safety of government debt.
Another $54 billion of 20-year bonds are expected over the next three months as the U.S. government ramps up spending to fund the economic recovery from the coronavirus pandemic.
Reporting by Chris Prentice in Washington; Editing by Sam Holmes & Shri Navaratnam