GMB union warns funding to Labour could drop by more than £1m 10 July 2013 Last updated at 02:13 Ed Miliband: "I do not want any individual to be paying money to the Labour Party in affiliation fees unless they have deliberately chosen to do so." The UK's third largest trade union has warned Labour to expect a significant cut in donations if Ed Miliband goes ahead with planned changes to the way its members donate to the party. GMB union funding could drop from around £2m a year to less than £1m. Under Mr Miliband's plan, union members would have to opt-in to pay subscriptions to Labour. The GMB's Paul Kenny told the BBC the move could see a 90% drop in the number of members affiliating to the party. An equally severe funding drop could see donations drop to around £300k. Mr Kenny, the GMB's general secretary, said it will ballot its members on whether they still want to give to Labour in September - meaning the funding cut could happen as early as next year, according to the BBC's industry correspondent John Moylan. Under the current system members are given the chance to vote on a union's political fund every 10 years. But Mr Miliband said on Thursday he would end the automatic "affiliation" fee paid to Labour by three million union members - 600k of whom are part of the GMB. Watershed moment The announcement came after Unite, one of the party's biggest donors, was accused of signing up its members to Labour in Falkirk - some without their knowledge - in an effort to get its preferred candidate selected. "This is an absolute watershed moment - the changes they are about to do will fundamentally change the party's relationship with trade unions and their members," Mr Kenny said. But Unite general secretary Len McCluskey said the political levy - worth £8m a year to Labour - would "stay as it is." Mr Miliband used his speech to say unions should have political funds "for all kinds of campaigns and activities as they choose" but individual members should not pay Labour any fees "unless they have deliberately chosen to do so." Members of both Unite and the GMB recently voted to maintain their political funds. He said the changes would have "massive financial implications" for the party, but could raise its membership from the current 200,000 to a "far higher number." The speech was welcomed by Mr McCluskey as well as former prime minister Tony Blair and others in the Labour Party who want to see a changed relationship with the trade unions.