* Vote reflect rise of protest, anti-business parties
* Parliament's position seen as too onerous on EU companies
By Robin Emmott
BRUSSELS, May 20 (Reuters) - The European Parliament voted on Wednesday to ban all products that contain "blood metals" sold by African warlords, but the legislation is likely to be blocked by EU governments who fear it would impose an unrealistic burden on business.
The surprise result marked a defeat for the pro-business European People's Party (EPP), the parliament's biggest grouping, who need fellow centrist allies to pass laws following last year's EU elections where protest parties did well.
The European Parliament voted 402 in favour versus 118 against with 171 abstentions on a proposal to require companies, including electronics firms, that buy gold, tantalum, tin and tungsten to certify imports do not finance warlords in Africa.
"Parliament votes for mandatory transparency against conflict minerals. Big success!" tweeted German Green Ska Keller after the vote in Strasbourg as some lawmakers broke out in applause while others stood in huddles, surprised by the result.
The result is set to paralyse the bill because European Union governments say firms across the 28 EU countries cannot track materials from small mines all the way through commodity exchanges to component manufacturers and the final product.
Greens, centre-left and protest lawmakers from the far-left and far-right gained critical mass in the vote to challenge a more pro-business proposal from the European Commission that would make blood-free certification only voluntary.
While party discipline is traditionally poor in the European Parliament, the result bodes poorly for the grand coalition that the centre-right and the centre-left had hoped to form to channel European Commission proposals through the 751-seat body.
Rights groups lobbied EU lawmakers to toughen up the Commission plan for a voluntary scheme, in a campaign backed by filmmaker Edward Zwick, whose hit "Blood Diamond" chronicled how gemstones financed war in Sierra Leone.
Campaigners and some EU lawmakers said Europe should echo the U.S. law that requires companies such as Apple to check their suppliers use only "conflict-free" metals.
But centre-right EU lawmaker Iuliu Winkler, who wants only smelters and refiners to be required to certify their imports, said the U.S. law was a failure because U.S. companies now try to avoid doing business with sub-Saharan Africa.
"In the Democratic Republic of Congo, this has meant even fewer legal jobs, a surge in smuggling, no taxes paid, thousands of people deprived of their livelihood," said Winkler.
The United States defines the conflict mineral zone as the Democratic Republic of Congo and neighbouring countries including Angola and South Sudan. They make up 17 percent of the global production of tantalum, 4 percent of tin, 3 percent of tungsten and 2 percent of gold.
The scheme does not cover diamonds because the European Union is already part of the 50-member Kimberley Process, an initiative set up in 2002 to control the use of rough diamonds that fund rebel movements and human rights abuses. (Reporting by Robin Emmott, editing by David Evans)