Wallonia's Belgian region rejected new amendments to a planned EU-Canada free trade agreement on Thursday, reaffirming its opposition and so threatening the entire deal, a flagship of European Union trade policy.

All 28 EU governments support the Comprehensive Economic and Trade Agreement (CETA), but Belgium cannot give assent without backing from five sub-federal administrations and French-speaking Wallonia has steadfastly opposed it.

Failure to strike a deal with such a like-minded country as Canada would call into question the EU's ability to forge other deals and damage credibility already battered by Britain's vote to leave the bloc and disputes over the migration crisis.

The moves came as leaders began a two-day EU summit in Brussels with trade policy the main topic set for Friday. European Council President Donald Tusk, chairing the summit, said in a tweet that the Europe's credibility was at stake.

Wallonia is home to some 3.5 million people, less than 1 percent of the 507 million Europeans CETA would affect. The European Commission, which negotiates trade deals for the bloc, offered new concessions in the form of changes to an EU declaration to be appended to the treaty. One EU diplomat said these sought to answer Walloon concerns about farming and how trade disputes with Canadian companies would be settled.

Walloon premier Paul Magnette called an emergency session of his government and was due to address the Walloon parliament on Friday. The government recognised improvements, but believed they did not go far enough, an official said, adding it needed time to reflect. The Belgian region of Wallonia rejected new amendments to a planned EU-Canada free trade agreement on Thursday, reaffirming its opposition and so threatening the entire deal, a flagship of European Union trade policy.

All 28 EU governments support the Comprehensive Economic and Trade Agreement (CETA), but Belgium cannot give assent without backing from five sub-federal administrations and French-speaking Wallonia has steadfastly opposed it.

Failure to strike a deal with such a like-minded country as Canada would call into question the EU's ability to forge other deals and damage credibility already battered by Britain's vote to leave the bloc and disputes over the migration crisis.

The moves came as leaders began a two-day EU summit in Brussels with trade policy the main topic set for Friday. European Council President Donald Tusk, chairing the summit, said in a tweet that the Europe's credibility was at stake.

Wallonia is home to some 3.5 million people, less than 1 percent of the 507 million Europeans CETA would affect.

The European Commission, which negotiates trade deals for the bloc, offered new concessions in the form of changes to an EU declaration to be appended to the treaty. One EU diplomat said these sought to answer Walloon concerns about farming and how trade disputes with Canadian companies would be settled.