* Draghi holds rates steady but seems open to more stimulus
* Yellen reiterates supportive Federal Reserve view
* Separatists ignore Putin calls to postpone Ukraine secession vote
* China exports, imports beat forecast (Updates to close of U.S. trading)
By Ryan Vlastelica
NEW YORK, May 8 (Reuters) - Stock markets around the world mostly rose on Thursday, gaining on positive comments from central banks, though U.S. shares ended flat as an early rally faded.
European shares climbed 1.1 percent after European Central Bank President Mario Draghi was seen as opening the door to more stimulus measures in June.
The ECB stance pushed the euro down 0.4 percent against the dollar. It previously rose to its highest level since November 2011.
In the United States, Federal Reserve Chair Janet Yellen, speaking to the Senate Budget Committee, repeated a statement she made on Wednesday that she expects improved year-over-year growth, though weakness in the housing sector could undermine that forecast.
Her comments were seen as indicating continued support for the economy, and U.S. shares rose for much of the session, though they turned lower in the afternoon after nearing record levels.
“We got right to resistance, we challenged it, but had no momentum to get through,” said Ken Polcari, director of the NYSE floor division at O‘Neil Securities in New York. “There was no surprise from Yellen, the ECB could have helped the market but that hasn’t happened; there’s just not enough momentum.”
The Dow Jones industrial average ended up 32.43 points, or 0.20 percent, at 16,550.97. The Standard & Poor’s 500 Index was down 2.58 points, or 0.14 percent, at 1,875.63. The Nasdaq Composite Index was down 16.18 points, or 0.40 percent, at 4,051.50.
The MSCI International ACWI Price Index rose 0.2 percent.
The 10-year U.S. Treasury yield was up 2/32, with the yield at 2.6125 percent. The U.S. dollar index, which measures the greenback against a basket of currencies, rose 0.3 percent and the greenback rose 0.3 percent against the yen.
The tense situation in the Ukraine weighed as pro-Russian separatists in eastern Ukraine ignored a public call by Russian President Vladimir Putin to postpone a referendum on self-rule, declaring they would go ahead on Sunday with a vote that could lead to war.
Gold, viewed as a safe-haven asset, was flat on the day after dropping more than 1.5 percent over the previous two sessions. Copper rose 1.1 percent after trading flat for much of the session.
In Asia, China’s exports and imports returned to slight growth in April after a surprise fall in March, offering signs that Beijing’s use of targeted policy measures to underpin growth may be starting to stabilize the economy.
U.S. crude futures fell 0.5 percent and Brent crude was off 0.1 percent. Traders continued to watch the situation in Ukraine, as well as Chinese crude imports, which jumped to a record high. (Additional reporting by Rodrigo Campos; Editing by Dan Grebler)