Hundreds of thousands of workers will be "thrown to the wolves" today as Tory cuts to employment rights come into force.

Unions warn that the changes will grease the wheels of public-sector privatisation by making takeovers far more attractive to greedy outsourcing firms.

Protection for anyone whose employment falls into the hands of new owners has been slashed.

It means it will be far easier for unscrupulous bosses to force down pay and conditions of any workforce they take over.

Low-paid workers in commonly contracted-out services such as cleaning, catering and social care are among the people most at risk from the changes.

In the past under Tupe rules - short for the Transfer of Undertakings and Protection of Employment - staff terms were automatically protected when their employer changed hands through a takeover or sale of the business.

But from today new owners will be able to tear up collective agreements within 12 months of taking over.

TUC general secretary Frances O'Grady said: "This is a deliberate bid by government to make privatisation cheaper and quicker.

"The government is sending a clear signal to employers that the rights and pay of low-paid workers are not important at a time when living standards are being hugely squeezed."

Construction union Ucatt general secretary Steve Murphy said: "Reducing the Tupe regulations will make it easier for employers to cut pay and conditions and make workers redundant.

"Long-serving and dedicated workers can be simply thrown to the wolves under the weakened regulations," he said.

"This gives construction workers particularly those working in maintenance further fears for their continued employment and comes on top of pay freezes and other recent attacks on their conditions."

Minister for Employment Relations Jenny Willott said: "By making these changes we will give businesses more clarity about conducting transfers and provide them with the tools to create new opportunities in the UK labour market, whilst protecting fairness for all."