BRUSSELS, July 3 (Reuters) - EU countries are wavering

over whether to back additional tariffs on Chinese-built

electric vehicles, highlighting Brussels' challenge in building

support for its largest trade case yet as Beijing threatens

wide-ranging retaliation.

Germany, whose carmakers made a third of their sales last

year in China, wants to stop the tariffs, according to a

government source, while France has been among the firmest

backers.

But a majority of countries are still weighing the pros and

cons of the escalating trade spat, according to an informal poll

by Reuters of EU governments.

The issue will be put to members in an advisory vote in the

coming weeks, the first official test of support in a landmark

case for the Commission. The EU initiated the probe without an

industry complaint, the first such trade case of this kind.

The bloc is set to confirm on Thursday provisional duties of

up to 37.6% on Chinese brands such as BYD, Geely

and SAIC, as well as on China-made models

of Tesla, BMW and other western automakers.

EU members will also vote in October if the Commission

proposes multi-year tariffs at the end of its investigation.

These would be blocked if a "qualified majority" if at least 15

countries representing 65% of the EU population votes against

them.

France, Italy and Spain, with 40% of the EU population, have

indicated they would back tariffs.

"Europe must defend itself if our companies are harmed and

do not compete on equal terms," Spain's economy ministry said.

However, the Czech Republic, Greece, Ireland and Poland were

still debating the issue, official and government sources said,

while Belgium has a caretaker government and the Dutch only got

a government this week.

NEGATIVE EFFECTS

Germany has stressed the need for a negotiated solution with

Beijing. Its automakers have said tariffs are the wrong

approach, with the negative effects outweighing any benefits.

Increasing the cost of EVs for consumers undermines the EU's

goal of being carbon-neutral by 2050, opponents say. Tesla has

said it will hike prices.

Beijing's retaliation could bring extra tariffs on EU

exports of cognac, pork or luxury cars.

The Commission says duties are needed to counter cheap

loans, land and raw materials and other subsidies and the goal

is a level playing field, not shutting Chinese car makers out,

as the United States' planned 100% tariff is likely to do.

Tariffs could also give the EU leverage in negotiations with

Beijing and push producers to make cars in the EU.

Hosuk Lee-Makiyama, director of thinktank the European

Centre for International Political Economy, said clear

majorities either way could embolden tariff opponents or

supporters. He added final positions at the end of the

investigation will depend on what Beijing offers in

negotiations.

"If we go to a vote then, it means negotiations have

failed," he said.

The EV investigation could just be the start for the EU as

it toughens its stance on Beijing, as its green and tech

companies trail global rivals, interviews with half a dozen

trade experts show.

They point to a 712-page updated report on Chinese state

interference and subsidies released in April as the strongest

sign yet that Brussels means business.

The document is by far the most extensive undertaken by the

Commission, showing it has learned a lesson from an

investigation into Chinese solar panels a decade ago, when it

did not impose tariffs and the EU's own industry collapsed.

It offers proof to back its assertions that China does not

play by the same rules and includes research into a wider range

of industries, beyond traditional ones such as steel, including

semiconductors, telecom equipment and renewable energy.

That leaves the door open to future cases.

"This is a report to set the scene and show how and why

Europe is changing its policies," said Alicia Garcia Herrero, a

senior fellow at Brussels-based economic thinktank Bruegel. "To

be frank, it's also a message especially for the German

chancellery."