(BUTTON) [ ] Show captionThe latest workers to go on strike are CWU postal workers. Photograph: Adrian Dennis/AFP/Getty Images Labour -- Support for striking workers declared by 600 Labour councillors Exclusive: Open letter puts pressure on party’s stance on strikes amid talk of coordinated autumn action Rowena Mason Deputy political editor -- More than 600 Labour councillors have declared their full backing for all rail, postal, dock and other workers on picket lines, as the party comes under continuing pressure over its stance on strikes. Amid a wave of strikes over pay and increasing talk of coordinated industrial action this autumn, the councillors signed an open letter saying they offered “full solidarity and support” to the Rail, Maritime -- (CWU), Unite and others. The latest workers to go on strike are CWU postal workers who rejected a 5.5% pay rise in return for changes to their conditions, while the RMT is planning a further round of rail strikes in the autumn. There are also 1,900 dockworker members of Unite at Felixstowe, the country’s biggest port, on an eight-day stoppage. However, the issue of strikes is a vexed one for Labour. Keir Starmer, the party’s leader, has expressed sympathy with the aims of striking workers, but the party’s whips have asked frontbenchers not to appear -- properly conducted. Starmer’s equivocal stance on strikes has annoyed Labour’s trade union funders. Sharon Graham, the Unite general secretary, told the Observer earlier this month: “There’s no point giving money to a party that is -- Ahead of the Trades Union Congress in September, senior union officials have begun to talk more of scheduling strikes for the same time for maximum impact or staggering them for effect. -- * Industrial action * Rail strikes * Trade unions * Keir Starmer