The shopworkers' union has urged MPs to vote against the suspension of Sunday trading laws during the Olympics when the move comes before Parliament on Monday.
Usdaw said the vast majority of shopworkers and retailers opposed extending opening hours in England and Wales for eight Sundays from July 22.
The union accused the Government of trying to force through the Sunday Trading (London Olympic Games and Paralympic Games) Bill after just five hours' debate in the House of Lords and of denying its own MPs a free vote on the issue.
John Hannett, Usdaw general secretary said: "Usdaw members want MPs to put family, sport and the Olympics first tomorrow by voting against this ill-conceived and rushed piece of legislation. Its only cheerleaders are Government and corporate interests who want to see a permanent deregulation of Sunday trading.
"The vast majority of shopworkers don't want to work extra hours on a Sunday and they quite rightly blame their increasingly difficult struggle to maintain a semblance of normal family life on the twin demands for more flexibility and unsocial working hours. These demands also reduce the opportunity of workers and their children to participate in organised sports and leisure activities.
"The suggestion that the success of the Games is any way dependent on large shops in Lancaster or Lincoln being open for 168 hours a week rather than 150 is nonsense and an insult to both to the Olympic Games and a world city like London.
"Worse still, enabling people to go shopping during Olympic events is actually being put ahead of enabling families to watch and enjoy the Games together.
"Ministers say shopworkers can opt out of Sunday working but while that right remains crucial, it won't help the thousands who already work Sundays and may be pressurised into working extra hours against their will. Ministers also claim it is only a temporary measure yet haven't even ruled out making a move for full deregulation during this Parliament."
A Business Department spokesman said: "The Olympics present a once in a lifetime opportunity to showcase London and the whole of the United Kingdom. By temporarily suspending Sunday trading laws we will enhance the visitor experience and provide a real boost to the economy.
"This Bill is not a test case for a future permanent relaxation of the Sunday trading rules and will only last for the duration of the Games. The suspension will allow more flexibility over the Olympics period, for shoppers, retailers and workers alike."