Trade unions have slammed new laws enforceable from today that allow companies to covertly spy on employees.

Under the Lawful Business Practice Regulations section of the the Regulation of Investigatory Powers Act (RIPA) firms have “routine access” to employees’ phone calls and emails.

But union chiefs say the new law conflicts with Article 8 of the Human Rights Act. This asserts that "everyone has the right for his private and family life, his home and his correspondence".

Trades Union Congress (TUC) spokeswoman Sarah Veale said: "We can't see how the two laws don't come into conflict. We think it’s likely a union will instigate a court challenge soon."

RIPA is “owned” by the Department of Trade and Industry, which recently outlined cases in which business and public authorities are allowed to record or monitor communications without the caller's consent.

These include "gaining routine access to business communications", as well as "monitoring standards of service and training" and “combating crime, and the unauthorized use of company systems”.

The TUC argues that the regulations give bosses too much power over employees and is calling for a "code of practice".

A draft code of practice issued by independent data-protection body, the Data Protection Commission contradicts the new RIPA laws.

The code says blanket monitoring of emails is unjustified and that employers should not open employees’ personal messages.