By Tarek Amara
TUNIS (Reuters) - Tunisia's powerful labour union said on Monday it would hold a national strike over wages and the economy after refusing to take part in a limited dialogue proposed by the president as he rewrites the constitution.
With more than a million members, the UGTT is Tunisia's most powerful political force and its call for a strike may present the biggest challenge yet to President Kais Saied after his seizure of broad powers and moves to one-man rule.
Saied has focused on his political agenda since last summer when he brushed aside the parliament and discounted most of Tunisia's democratic constitution to say he would rule by decree despite a gathering economic crisis.
The president's opponents accuse him of a coup that has undermined the democratic gains of the 2011 revolution that triggered the Arab spring, but he says his moves were legal and needed to save Tunisia from a prolonged political crisis.
The union has demanded a meaningful national dialogue on both political and economic reforms, but it rejected Saied's proposal that it join a small advisory group of other civil society organisations that could submit reform ideas.
Saied said last week that political parties would be barred from a role in forming the new constitution, which would replace the 2014 document that emerged from an inclusive debate among Tunisia's main political factions and social organisations.
"We reject any formal dialogue in which roles are determined unilaterally and from which civil and political forces are excluded," UGTT spokesperson Sami Tahri said.
Tunisia's major political parties pledged to fight Saied's decision to exclude them from key political reforms including the drafting of a new constitution and accused him of seeking to consolidate autocratic rule.
Achaab, the newspaper of the union, said that Saied met with UGTT leader on Sunday and informed him that he insisted that the dialogue will be in its current formula that he proposed.
The date of the strike, by UGTT members working in public services and state companies, will be announced later, Tahri said.
Saied's government is in talks with the International Monetary Fund for a bailout, seen as necessary to ward off national bankruptcy, but the UGTT has rejected proposed spending cuts and instead wants wage increases for state workers.
(Reporting by Tarek Amara; writing by Angus McDowall; editing by Philippa Fletcher, Andrew Heavens and Ed Osmond)