* Voestalpine says up to 3 pct of group sales affected
* Thyssenkrupp supplies 400,000-500,000 tonnes/year to U.S.
* Voestalpine shares down 1.9 pct, Thyssenkrupp down 0.1 pct
FRANKFURT/LONDON, March 9 (Reuters) - New U.S. tariffs on steel and aluminium imports took a toll on European Union steelmakers' shares on Friday, although two of the bloc's top players said the move by the world's largest steel importer will have a limited impact on them.
However, Germany's steel association called on the EU, the biggest exporter of steel to the United States, to come up with effective countermeasures, warning the bloc might be forced to absorb more volumes by the move.
U.S. President Donald Trump slapped import tariffs of 25 percent on steel and 10 percent on aluminium on Thursday, exempting Canada and Mexico and offering the possibility of excluding other allies.
The EU accounted for a fifth, or $6.8 billion, of U.S. steel imports last year, the German statistics office says. The EU said its base case was that it will be excluded from the U.S. tariffs, although it will go to the World Trade Organization to impose its own measures if Washington presses ahead.
Shares in ArcelorMittal, Europe's biggest steelmaker, were down 1.4 percent, while India's Tata Steel's shares fell 5 percent. The U.S. represents around 10 percent of Tata Steel Europe's sales, an industry source said.
"I'm asking for moderation. The EU is able to react decisively on the basis of World Trade Organization rules. Now it's about not stoking a global trade war," Dieter Kempf, president of Germany's BDI industry association, said.
"A new wave of protectionist measures would quickly hit Germany," he said, adding about one in of every four jobs in Germany depends on exports.
Shares in Salzgitter, Germany's second-largest steelmaker, were down 4.3 percent. The group did not respond to requests for comments, but its CEO said on Thursday that markets were overestimating the impact of the tariffs on its business.
While the United States imported 36 million tonnes of steel in 2017, with Canada, Brazil and South Korea the leading suppliers, that was less than 8 percent of global steel market traded volumes of 473 million tonnes during the year.
And although tariffs would price some imports out of the U.S. market, analysts at consultants Wood Mackenzie estimate that at most 18 million tonnes would be diverted to other markets - or less than 4 percent of annual traded volumes.
"The extent to which other sales are affected by import restrictions is being thoroughly examined," Austrian steelmaker Voestalpine said in a statement.
"A maximum of about 3 percent of current Voestalpine group sales can be affected by the U.S. tariffs and the economic risk remains very manageable even in extreme cases," Voestalpine said, adding it expects to see further exemptions.
Thyssenkrupp, Germany's largest steelmaker, said it supplies only 400,000-500,000 tonnes of steel a year to the U.S., between 3.3-4.5 percent of total deliveries.
Shares in Voestalpine were down 1.9 percent, while Thyssenkrupp's were 0.1 percent lower.
Swedish steelmaker SSAB said it expected a two-fold impact from the U.S. tariffs, with a negative impact in Europe mitigated by a positive impact in the United States.
SSAB generates most of its sales in Europe, but it is also one of the largest steel plate producers in the United States. .
A source at a major European steel producer said despite China's massive capacity cuts in steel over the past two years, he was concerned they would redirect cheap steel sales to Europe following the Trump tariff move.
China produces half the world steel and accounts for about a fifth of world steel exports.
Ratings agency Moody's has said the tariffs are credit negative for European steelmakers.
An industry source at a major European steel producer said the Trump tariffs would upend his firm's business model to an extent, because it is based on growing sales mostly to the U.S.
(Additional reporting by Michael Shields in Zurich and Tom Kaeckenhoff in Duesseldorf; Editing by Alexander Smith)