BRUSSELS (Reuters) - The premier of Belgium's Wallonia region insisted ahead of a crisis meeting of regional leaders with Prime Minister Charles Michel that he would not agree to an EU-Canada trade deal under pressure.

"Every time you try to put an ultimatum it makes a calm debate and a democratic debate impossible," Paul Magnette said on arrival at the meeting in Brussels, hours before EU leaders say they will cancel this week's signing of the CETA pact unless Belgium gives its consent.

"We don't need an ultimatum," Magnette told reporters. "We will not decide anything under an ultimatum or under pressure."

Michel cannot add the consent of Belgium to that of the other 27 EU member states without backing from five regional authorities. Socialist-led Wallonia and French-speaking allies in southern Belgium are withholding that.

"We are not against a treaty with Canada," Magnette said. "But we won't have one that jeopardizes social and environmental standards and the protection of public services and we want absolutely no private arbitration mechanisms."

(Reporting by Robert-Jan Bartunek and Philip Blenkinsop; Writing by Alastair Macdonald)