Rome - Italy's largest labour union federation signalled the start of a four-hour nationwide strike Friday with a march by hundreds of its members down the streets of a rainswept Rome.

The leftist CGIL federation is protesting what it says is Silvio Berlusconi's centre-right government's "inadequate" response to salaries, pensions and education reform.

However, the strike is being viewed as a show of strength by the CGIL after the country's other two main union groupings, the more moderate CISL and UIL, refused to participate, branding the work stoppage "irresponsible."

CGIL said Thursday its members working for the country's public railways and for subway, bus and tram services in Rome and Milan, would not adhere to the strike so as not to exacerbate disruptions and damage caused by bad weather.

Torrential rain has hit several Italian cities including Rome, where the Tiber threatened to overflow its banks in some areas while Venice's St. Mark's Square remained submerged in water due to exceptionally high tides.

Labour protests in Italy, whose economy slid into recession last month, have resulted in a loss of some 2.5 million production hours, according to the country's main industrialists lobby group. (dpa)