Spanish unions are holding a general strike a day before the Prime Minister Mariano Rajoy announces new austerity budget to meet strict guidelines set by Eurozone leaders.

Some strikers attempting to disrupt bus service were detained police early Thursday in Madrid.

The strike is expected to have limited impact on public services including bus, rail, air transportation.

Thousands of demonstrators rallied Wednesday in Madrid ahead of the strike.

The unions argue the reforms proposed by the prime minister will make it cheaper to fire workers and more difficult to gain salary increases.

Rajoy says the labor reforms under consideration by the parliament are necessary to reduce high unemployment.

Reuters says eurozone finance ministers are expected to take a closer look at Spain's plans for dealing with its debt during their meeting Friday.