BRUSSELS (Reuters) - The European Commission will propose next week a simple approval procedure for a planned EU-Canada trade deal in a bid to speed up the adoption of an agreement seen as a controversial in many EU capitals.

Commission President Jean-Claude Juncker told EU leaders meeting on Tuesday that the Commission would make its proposal on July 5 that the Comprehensive Economic and Trade Agreement (CETA) would be an "EU-only" agreement, an EU official said.

This would mean it would be adopted if backed by representatives of member states and by the European Parliament.

The deal would not apply to Britain, which has voted to leave the EU, once it has formalized its exit.

Trade Commissioner Cecelia Malmstrom has said she hoped CETA is adopted before the end of October when it could be signed during a planned visit to Brussels by Canadian Prime Minister Justin Trudeau.

Most European Union members have said they viewed the deal as a "mixed" agreement, meaning each country would have to push the deal through their parliaments, a move that would likely delay approval.

Belgium's regional parliament of Wallonia, one of four such assemblies that would scrutinize the deal, has said it would oppose it.

Bulgaria and Romania have also expressed reluctance given Canada does not extend its visa-waiver entry system to their citizens.

The Commission, which negotiates trade agreements on behalf of the 28 EU members, and Canada say CETA could increase trade between the two by some 20 percent.

However, the deal is facing opposition from campaign groups and trade unions, who say CETA is as dangerous as their bete noire, a planned EU-U.S. trade deal called the Transatlantic Trade and Investment Partnership (TTIP). They say the deals hand power to multinationals and are a threat to democracy.

Groups in Austria and Germany, which proponents say would benefit most from a trade deal, have staged a series of anti-TTIP and CETA rallies, with a large demonstration planned in Berlin on Sunday.

Juncker also urged EU leaders at the summit to back free trade talks with the United States in the face of growing scepticism in member states.

(Reporting by Francesco Guarascio and Philip Blenkinsop; Editing by Ruth Pitchford)