The charges were made in a report in the Sunday Times that claimed the online retailer, which employs thousands of casual workers in Britain around this time of year, refuses to allow sick leave even if staff have a doctor's note.
The report said that workers who take sick leave receive a penalty point and six penalty points can result in dismissal.
The paper said that staff are made to work a compulsory 10.5 hour overnight shift at the end of a five-day week, which means that, because it runs over Saturday night and Sunday morning, staff are working every day of the week.
Furthermore the report claimed staff were set quotas for the number of items to be picked or packed with staff packing Xbox 360 games consoles having to pack 140 per hour.
Staff who fail to meet their quota lose out on bonuses to other staff. In addition they can end up walking up to 14 miles a day to collect items for packing.
During each eight-hour shift staff are allowed only one break of 15 minutes and another of 20 minutes. Staff also need permission to go to the toilet.
The tough conditions come against a backdrop of booming orders and profits. Amazon globally pulls in almost 1m orders a day with Amazon scheduled to take as much as $7.2bn in the fourth quarter - its busiest time of year.
The Sunday Times complied its report after a tip off and sent a reporter undercover to the retailer's warehouse in Bedfordshire as a packer.
In response to the report Allan Lyall, vice -resident of EU Operations for Amazon, told the paper: "We want our associates to enjoy working at Amazon.co.uk and the interests of all workers are represented by a democratically elected employee forum who (sic) meets regularly with senior management.
"This forum was consulted before the workforce elected to reduce breaks to 15 and 20 minutes on an eight-hour shift in order to cut the total working day by half an hour.
"Demand for permanent roles from our temporary employees is at such a high level that we no longer need to recruit externally for permanent positions. Indeed, we have already seen well over 100 temporary employees become permanent this year alone."