The UGTT union has urged its one million members to observe the strike across the country to protest against government plans for a wage freeze and cuts in subsidies, aimed at securing a $4bn (£3.3bn) loan from the International Monetary Fund to ease Tunisia's economic crisis.

Flights to and from Tunisia are being halted as a result of the industrial action.

The union says its motive is not political, but it is bound to be seen as another challenge to President Saied, who has effectively assumed one-man rule for the past year.

The UGTT is in any case already caught up in a showdown with the government after it refused to engage in Mr Saied's plans for a new constitution.

The next 24 hours are likely to see the fault lines in Tunisia become even sharper.