Union leaders have warned of industrial action "on an industrial scale" against the Government's plans to slash public-sector spending.
Dave Prentis, of Unison, made the threat amid preparations for a series of union conferences this month, saying, "The economy is still in intensive care, but the Government's medicine is not working.
"We know that worse lies ahead. After the double bank holiday feel-good factor wears off, the reality of austerity Britain will kick back in. For public sector workers and the people who rely on them, for the sick, the vulnerable, the elderly, the jobless and those seeking to better themselves through education, the future is bleak.
"Unless this Government changes direction, it is heading for industrial turmoil on a massive scale. The government must understand that Unison will fight tooth and nail to protect and defend public services, and will ballot one million of its members to strike to protect their pensions.
"This will not be a token skirmish, but a prolonged and sustained war, because this government has declared war on a huge proportion of the population.
Mark Serwotka, of the Public and Commercial Services union, said the cuts were unfair.