* Trump threatens tariffs on EU over long-simmering aircraft row
* IMF cut global economic outlook
* Oil prices near 5-month high
* Asian stock markets: tmsnrt.rs/2zpUAr4
By Hideyuki Sano
TOKYO, April 10 (Reuters) - Asian shares stepped back from eight-month highs on Wednesday as the IMF lowered its global growth outlook and as tensions over tariffs between the United States and Europe escalated.
MSCI's broadest index of Asia-Pacific shares outside Japan dropped 0.1 percent, a day after it hit eight-month highs while Japan's Nikkei lost 0.9 percent. On Wall Street, the S&P 500 gave up 0.61 percent and the Nasdaq Composite declined 0.56 percent.
MSCI's broadest gauge of the world's stock markets dipped 0.1 percent on Wednesday from Tuesday's six-month peak but it is still almost up 19 percent from its low marked in December, which was its lowest level in almost two years.
Although earnings forecasts have been pegged back recently, share markets have been propped up by hopes of a trade deal between Washington and Beijing and optimism that the Chinese economy may be bottoming out on policy support.
"The gap between the strength in global shares and sluggishness in the real economy has been widening," said Norihiro Fujito, chief investment strategist at Mitsubishi UFJ Morgan Stanley Securities.
That view was reinforced on Tuesday when the International Monetary Fund cut its forecast for world economic growth this year, saying the global economy is slowing more than expected and that a sharp downturn could require world leaders to coordinate stimulus measures.
U.S. data overnight added to the cautious mood, with job openings dropping to an 11-month low in February and raising doubts about the strength of U.S. labour market, which has so far been one of the few bright spots in the economy.
Global trade anxiety was another sore point for risk asset markets.
U.S. President Donald Trump threatened to impose tariffs on $11 billion worth of European Union products, heightening tensions over a long-running transatlantic aircraft subsidy dispute.
The move came as markets remain on edge as negotiators try to hammer out trade deals with China and neighbours Mexico and Canada.
Global debt yields held mostly steady, with the 10-year U.S. Treasuries yield at 2.501 percent, off its 15-month low of 2.340 percent touched late last month.
In a possible sign of investors' strong appetite for bonds, Saudi Aramco is set to raise $12 billion with its first international bond issue after receiving more than $100 billion in orders.
It was a record breaking vote of market confidence for the oil giant despite concerns sparked after the murder of Saudi journalist Jamal Khashoggi in October.
Major currencies were little moved with an immediate focus on the European leaders' summit and the European Central Bank's policy meeting.
European Union leaders are likely to grant British Prime Minister Theresa May a second delay to Brexit but they could demand she accepts a much longer extension as France pushed for conditions to limit Britain's ability to undermine the bloc.
The euro held firm at $1.1266, extending its slow recovery from $1.1183 touched on April 2. It is up 0.43 percent so far this week. The British pound perked at $1.3059, little changed on the day.
The dollar slipped to 111.14 yen, having fallen 0.5 percent so far this week.
Oil prices held firm after hitting five-month highs the previous day as fighting in Libya raised supply disruption concerns.
U.S. crude futures stood at $64.23 per barrel, up 0.3 percent in early Asian trade after rallying to a five-month high of $64.79 on Tuesday.
Brent crude futures changed hands at $70.83 per barrel, not far from Tuesday's five-month peak of $71.34. (Editing by Shri Navaratnam)