Charities claim the localised postal walkouts have had a damaging effect on donations and fund-raising campaigns.

The Institute of Fundraising's director of policy, Louise Richards, says the strikes could affect the Christmas campaigns if they continue.

Now that union members have voted in favour it doesn't look good: charities are already facing tough times thanks to the recession and strike action on top doesn't help, says Richards.

It's feared the strike will have an adverse affect on charities' fundraising campaigns as mail drops will be behind.