New regulations allowing town halls to use agency staff to cover strikes are based on an old consultation ditched as ‘not fit for purpose' by an official watchdog, Unison has warned.

Britain's largest trade union, which represents hundreds of thousands of council staff threatening strikes over pay amid soaring inflation, says controversial changes to the Conduct of Employment Agencies and Employment Business Regulations 2003, which came into force on 21 July, are unlawful.