Canadian and European leaders formally concluded a free trade agreement that is widely seen as a template for a larger pact between the EU and the United States.
The text of the deal, which is 1,600 pages long, was published and now the long ratification process will begin, amid lingering concerns from some EU member states.
Germany, in particular, has pressed for a contentious arbitration mechanism to be excluded from both the Canada deal and an eventual EU-US Transatlantic Trade and Investment Partnership.
The "investor-state dispute settlement" provision will allow private investors to sue governments if they feel local laws threatened their investments, and idea opposed in Berlin.
Romania and Bulgaria may also try to block the deal because their citizens are required to have visas to travel to Canada, reportedly to stop a feared wave of refugee claims by ethnic Roma.
But EU Trade Commissioner Karel De Gucht warned a German newspaper on Thursday that no changes can be made to the deal without killing it.
"If we re-open negotiations on CETA (the Comprehensive Economic and Trade Agreement), the deal will be dead," De Gucht told the daily Frankfurter Allgemeine Zeitung on Thursday.
At a joint press conference in Ottawa yesterday with European Council President Herman Van Rompuy and Canadian Prime Minister Stephen Harper, EU Commission President Jose Manuel Barroso said the pact "was fully backed by all member states of the European Union including Germany."
"It would be very strange," he added, if Germany tried to block the deal which will benefit Germany the most as the EU's largest economy and exporter.
Canada, meanwhile, pledged in a statement to remove its visa requirement on Bulgarian and Romanian travellers "as soon as possible."
After the text is translated into 23 languages and the wording is scrutinized for accuracy by lawyers, CETA will be signed next year and come into force in 2016, Barroso said.
The pact will eliminate 98 percent of tariffs on goods and services, increase cross-Atlantic worker mobility and harmonize professional qualifications.
Hundreds of millions of dollars in duties will be eliminated.
The EU will notably gain access to bid on Canadian federal, provincial and municipal government procurements and public contracts estimated to be worth more than Can$150 billion, and which had been closed to all but local firms.
