Workers at a leading Methodist charity have backed industrial action in a dispute that follows years of discontent over pay.

Senior executives at Action for Children were urged to resolve the long-running dispute through the conciliation service Acas as members of Britain's biggest union, Unite, backed strike and other industrial action.

More than seven in ten of Unite members taking part in the industrial action ballot at the charity voted yes to strike action. Nearly nine in ten backed industrial action short of a strike.

The strong vote in favour displays a depth of anger which cannot continue to be ignored, the union said.

The ballot came after the charity imposed a one per cent cost-of-living award for 2015/16, with 40 per cent of the workforce excluded from the award, according to Unite.

The union also said managers had removed contractual pay increments for new starters and cut mileage rates.

Unite and the public service union Unison began contacting some of the charity's celebrity supporters, including Jenny Agutter, Sir Trevor McDonald and Angela Rippon, to seek their backing.

Unite national officer Sally Kosky said: "Senior executives at Action for Children cannot continue to ignore the growing anger among its workforce. Many dedicated workers at the charity have seen their wages virtually frozen for the last five years, while the number of senior managers earning over £70,000 has gone up to 21.

"Staff helping vulnerable families up and down the country have grown increasingly frustrated with management's high handed approach. It does nothing for morale and nothing to recognise the invaluable contribution they make day in day out."

UNISON also urged managers at the charity to take steps to avoid a strike.

Of the UNISON members, more than seven in ten voted for strike action and more than eight in ten voted for industrial action short of a strike.

UNISON said staff have had their wages frozen since 2010, while the charity has benefited from surpluses of more than £5.4 million for each of the last three years.

Workers in the voluntary sector earn about 10 per cent less than those in the private sector

Simon Watson, Unison's national officer for the voluntary sector, said he has "a degree of sympathy" with charities hit by cuts in government contracts. "Many employees are being forced into extreme hardship," he told The Guardian. "Some are having to use the same food banks as the families they are trying to help."

Sir Tony Hawkhead, Chief Executive at Action for Children, said: "The role that trade unions represent in the workplace is highly regarded by Action for Children. Throughout the six-month process in 2015 during which we have been in discussions with the unions, we have made every effort to reach an agreement.

"In an organisation which has a workforce of nearly 5,000, there are around 1,100 trade union members, of which only a quarter of members voted. We are saddened by the ballot result, which in real terms means that only 5 per cent of staff backed industrial action.

"However, we respect the right of trade union members who choose industrial action. Our top priority is to ensure this has the minimum disruption to our frontline services. Action for Children exists to help the country's most disadvantaged children and families. We have been working closely with operational managers to put in place contingency plans with the aim of maintaining business as usual for people who depend on our services."

For more than 145 years, Action for Children worked in partnership with the Methodist Church. The charity's founder, Thomas Bowman Stephenson, was a Methodist minister from the North East of England with a passionate commitment to social justice. The charity's ethos is deeply rooted in Methodist principles.