Britain's equality commission says new rules for spies and soldiers on handling detainees held overseas are unlawful because they don't rule out the use of torture.

The Equality and Human Rights Commission was opening a legal challenge on Tuesday over revised guidelines published last July after concern over the actions of some British officials.

Britain's rules set out assurances that intelligence officers or soldiers must seek before interviewing people held overseas, or before asking others to question them on behalf of the U.K.

Lawyers for the commission claim the rules don't categorically rule out the use of torture, and could leave officials open to lawsuits.

Britain's government insists it does not use torture, and that the rules are lawful.