Campaign groups and shareholder activists could be among the first to use “derivative actions”, a new legal tool that comes into force on Monday as part of the 2006 Companies Act and offers expanded scope for holding company directors to account.

The Corporate Responsibility Coalition (Core) – which is backed by the likes of Amnesty, Friends of the Earth and Action Aid – is planning on Monday to circulate members with a guide to the act, which includes practical advice on how best to make use of it.

In a separate letter to Gordon Brown, Core is also urging the prime minister to set up a permanent advisory body on business responsibility issues. The letter, signed by two dozen organisations from Corner House to the Fairtrade Foundation, says they do not believe that relying on voluntary action by business “is alone sufficient to ensure positive change”.

Under the new Companies Act, derivative actions will allow shareholders, acting on behalf of their company, to sue one or more directors for alleged misconduct such as negligence or breach of duty. Importantly, and in contrast to the past, the new statutory rules will not require claimants to show such directors benefited personally or were fraudulent.

Other parts of the 2006 Companies Act coming into force on Monday also deal with directors duties – including a new duty to promote the success of the company for the benefit of its members.

Lawyers are cautious about making firm predictions over how the new “derivative action” mechanism is likely to be used. But they do point out that the act has introduced significant procedural protections to ensure that companies are not swamped by vexatious or headline-seeking litigation.

For example, shareholders must first persuade a court in two separate “permission” hearings to let a derivative action go ahead. Moreover, if the conduct at issue has been ratified by the majority shareholders, directors will have a complete defence.

Even so, litigation specialists still think that corporate boards should be alert to the new regime.

Michelle de Kluyver, lawyer at Allen & Overy, said: “I don’t think we buy into the scaremongering, but there are expanded risks [for directors].”