Two of Italy's biggest unions said on Wednesday they would stage a one-day strike on Dec. 12 to protest Prime Minister Matteo Renzi's labour and economic policies, marking a further escalation in recent social tensions, Reuters reported. It will be the first time in three years that the two unions, the CGIL and UIL, have staged a joint strike. Italy's other main union, CISL, has said it will not participate. The CGIL has about six million members and UIL 2.2 million. Union officials say they are protesting Renzi's plan to introduce more flexibility in hiring and firing rules, saying this will erode workers' rights. The government says the reform is needed to lift the flagging economy and attract investment.