Business leaders have accused Labour of returning to the bad old days of “beer and sandwiches at Number 10” following the announcement of plans to strengthen employment rights for up to 1.4m temporary and agency workers.

Other leading business organisations are incensed they were excluded from the negotiations between government, the Trades Union Congress and the CBI employers’ body, which hammered out last week’s deal entitling temporary workers to equal treatment with permanent staff after just 12 weeks in a job.