Trade unions are concerned that a new surveillance bill giving the government sweeping powers to access email and other encrypted Internet communications may conflict with the Human Rights Act.

Parts 1 and 4 of the Regulation of Investigatory Powers Act 2000 (RIPA) became law on Monday, but the most controversial parts of the law - email interception and encryption - take effect later.

A Home Office spokesman said: "The bulk of the Act came into effect at the same time as the Human Rights Act partly because we were making sure RIPA was completely compliant with the Human Rights Act."

Tap From October 24, companies have powers to tap phone calls or open emails sent by their employees without the employee's knowledge or consent, according to the Department of Trade and Industry (DTI), the agency overseeing that aspect of RIPA.

However, unions are questioning whether that contravenes Article 8 of the Human Rights Act, the portion that asserts "everyone has the right for his private and family life, his home and his correspondence" to remain private. The TUC argues that the regulations would give bosses too much power over their employees, and is calling for a "code of practice".

The Human Rights Act, established by the European Union and incorporated into UK law, allows citizens to go directly to courts to ensure their basic human rights are met. Since 1966, citizens have had to go through the much longer process of taking complaints to the European Court of Human Rights to seek redress.

The TUC wants to make sure that bosses are not allowed to "go on fishing expeditions" for private employee information and also want the prior notification rule reinserted into the act, Veale said.