Over a million public sector workers are taking industrial action against the Government in a series of rows over pay, pensions, jobs, conditions and spending cuts, according to union leaders - a figure disputed by the Government.
David Cameron believes disruption caused by today's public sector strikes is "wrong", his official spokesman said.
Asked whether the Prime Minister felt strikes in the public sector could ever be justified, the spokesman said: "Does the Prime Minister think that people in this country - parents, commuters, users of public services - should have their routines disrupted? Of course he doesn't think it is right."
Asked for the PM's assessment of the impact of today's strikes, the spokesman responded that Cameron would say "any disruption any user of public services experiences is wrong".
Union leaders said they were "overwhelmed" by support after a strike by public sector workers caused widespread disruption.
David Cameron, Michael Gove and other Government figures depicted in a variety of unflattering manners by striking public sector workers.
Hundreds of schools are to close tomorrow as teachers join strike action. Find out what schools in your area are affected.