The head of the Belgian region of Wallonia on Wednesday said he still refused to sign off on a EU-Canada trade accord and asked that a visit by Canadian premier Justin Trudeau be delayed.

Paul Magnette, the head of government of Wallonia, spoke a day after he received an ultimatum of Friday to allow Belgium's federal government to endorse the huge trade deal, known as CETA.

"We cannot sign by Friday. That is not reasonable," a combative Magnette told RTBF radio after EU ministers asked that he reverse course in time for a discussion on trade by European leaders set for Friday.

"I think that it is reasonable to delay indefinitely the meeting (with Trudeau set for October 27) because it's better to avoid what would seem like a confrontation," Magnette added.

"It's not because the Canadians are our friends that we must accept everything," said Magnette.

But in a sign that a breakthrough might be in the making, a spokesman for Magnette said Canadian Trade Minister Chrystia Freeland met the regional leader in the Walloon capital of Namur on Wednesday.

- 'Unravelling' -

Magnette later met with EU Trade Commissioner Cecilia Malmstroem and Belgium's pro-CETA Foreign Minister Didier Reynders in Brussels.

Magnette warned the commission, which handles EU trade talks, that his demands could only be met by reopening negotiations with Canada that were formally concluded two years ago.

"The treaty is already unravelling," Magnette said, citing concessions agreed with Germany, which was allowed on Tuesday to kill the deal if the German constitutional court should later decide against it.

Later an EU Commission spokesperson called the talks "constructive".

The issue will be discussed later by European leaders, the EU's executive arm said expressing the hope that "a solution is reached soon so that CETA can be signed during the EU-Canada Summit on 27 October".

While Magnette cited progress in his talks with the EU, he said differences remained too wide on a contested investor protection system that has become a hot-button issue for the anti-CETA movement.

A senior EU diplomat told AFP that the signature with Trudeau would need to be confirmed by Monday.

"Wallonia's deadline is Monday morning, otherwise Trudeau will not come," the source said.

The EU fears that the delay of CETA would be fatal to the deal and send a bad signal to the world that it is difficult to reach trade accords with Europe.

"I still believe that we can find a way forward and we can get it through," said European Commission vice president Jyrki Katainen at a news briefing.

Magnette has drawn big support from opponents to CETA, including Greenpeace and Foodwatch, that see the Canada deal as a Trojan horse for a far more ambitious trade accord between the EU and US, known as TTIP.

Both deals threaten environmental and consumer protection and offer big benefits to multinationals, the groups say.