EU states will find it harder to opt out of the Union's 48 hour maximum working week under new proposals.
How long is long enough?
The European Commission says it wants to tighten loopholes in its Working Time Directive in order to limit the time employees spend at work.
The changes would mean workers would be able to work more than 48 hours a week only if employers and unions reached a collective agreement.
The government has vowed to fight the plans when they come up for approval.
Any changes will need to be voted on by the European Parliament before they come into force.
UK business leaders have argued that the proposals will increase bureaucracy while unions said the proposed changes did not go far enough.
Under the current agreement, the UK is able to opt out from the 48-hour working week.
"The individual opt out from the 48-hour working week would remain possible but be subject to stricter conditions to prevent abuse," the EU's employment and social affairs commissioner Stavros Dimas said of the proposed changes.
"It is a balanced package of measures that protect the health and safety of workers whilst introducing greater flexibility and preserving competitiveness."
Under its proposals, the reference period for employers calculating working hours would be extended from four months to a year.
The Commission is also seeking to redefine working time to exclude time spent on call but not actually worked.
Digby Jones, director general of the Confederation of British Industry, said it should be up to individuals, not trade unions, to decide what hours they worked.
"If somebody wants to work longer hours to a limit, whatever it may be, it should be their individual choice.
"For a trade union in Britain to have the right to tell an individual how many hours they work is, frankly, harking back to another age."
"This is a disappointing decision which will satisfy no-one," said Brendan Barber, the TUC's general secretary.
"People at work will get some slight extra protection against bosses who try to force them to opt out of a 48 hour working week but these limited reforms show that the Commission has failed to grasp the scale of the UK's long hours culture.
"We are working just about the longest hours in Europe and yet our productivity performance is dismal."
LONG HOURS CULTURE?
UK working hours and efficiency compared
The Commission said it wanted to strengthen a worker's right to choose, as well as reinforce their ability to negotiate with employers.
Individuals will still have the power to opt out on their own, irrespective of the group decision.
Any worker doing so would have to renew the opt-out every 12 months.
Employers, meanwhile, would not be able to ask employees to sign an opt-out before they start work or during probation periods.
The UK government already has complained that the current legislation is costing British businesses billions of pounds every year, a sentiment that is echoed by groups such as the CBI.
The concern is that by further limiting the ability of companies and employees to work for longer, the labour market is likely to become less flexible and may hamper growth.
In a letter to the Commission, the TUC has warned that UK workers are going to be left exposed to dangerously long working hours.
The union estimates that nearly four million UK employees - about 15% of the total workforce - are regularly working over 48 hours a week.
Owen Warnock, a partner with Eversheds law firm, said the changes would result in much more paperwork for businesses.
"There is good news and bad news for employers but mostly bad news," he said.
"For most employers, this legislation will add a considerable burden of red tape and a lot of the practical difficulties have not been ironed out."