(By Emily Backus) Turin, September 4 - Fiat on Wednesday reached a deal with Italian trade unions that opens the doors to a major investment package for the Mirafiori plant in the carmaker's home city of Turin. Fiat pledged to invest just under one billion euros in the Mirafiori plant, said Rocco Palombella, the secretary general of the UILM union. Fiat CEO Sergio Marchionne said in a statement that the agreement made it possible to ''immediately start the investment plan necessary to guarantee the production and employment future of the Mirafiori plant''. He said it was a "brave" decision that confirmed Fiat's "commitment" to its Italian operations. The deal comes after a period of tension in which Fiat threatened that it could drop its commitments to investing in Italian plants due to problems in its industrial relations here. In July Marchionne blasted business in Italy saying, ''conditions in industrial Italy remain impossible'' and threatened to move production of new models of Alfa Romeo vehicles abroad. Fiat has been engaged in a long tussle with the left-wing FIOM union over its drive to introduce more flexible working practices in Italy to make the plants profitable. But on Wednesday the general secretary of the UIL union, Luigi Angeletti, said Marchionne had guaranteed that investments in Fiat's flagship Mirafiori plant in Turin would be made. Marchionne told union representatives that workers at Mirafiori would be temporarily laid off in October and put on CIG benefits while production lines are made ready for it to produce a Maserati SUV model. Ferdinando Uliano of the FIM union said the carmaker also planned to produce another model at Mirafiori in addition to Maserati SUV, while stressing that the company had not said when this would happen. The FIM-CISL secretary for Turin, Claudio Chiarle, said that, after investments at the city's Grugliasco plant that now makes the Maserati Quattroporte and Ghibli models, ''It is (now) Mirafiori's turn, thus completing Fiat's industrial strategy of focusing on high end and luxury brands to give full employment and high profit margins. ''It is a fundamental step for the workers of Mirafiori and Fiat's suppliers in Turin after years of CIG benefits, sacrifices, and economic suffering, which have prevented many Turin families from building a future, but who today can see new, concrete prospects,'' Chiarle added. FIM Secretary General Giuseppe Farina, meanwhile, said Marchionne has also confirmed Fiat would maintain its commitments to invest in other Italian factories.