The new guidance, which is now out for consultation, makes it clear that charities are allowed to campaign in countries that don't have human-rights legislation.
Previously, Amnesty believed it was barred from campaigning as a charity to end human-rights abuses in countries such as Saudi Arabia.
Worldwide campaigns against human-rights infringements such as the death penalty have been limited to the main Amnesty organisation, rather than involving its charitable arm.
But that could change following the commission's revised guidance, allowing Amnesty to move more of its work to its charitable arm, the Amnesty International UK Trust, which currently comprises around 40 per cent of the organisation.
Amnesty International UK's finance director, Melvin Coleman, said: "The new guidance certainly makes it possible to carry out a lot more of our activities through the charitable arm. But we have to look at the fine details of the proposals."
Third Sector understands that Amnesty is unlikely to convert entirely to charitable status and will leave at least part of the organisation as a non-charity.
The commission's director of legal services, Kenneth Dibble, said: "Promoting human rights can be a difficult area and many charities don't realise how much freedom they have. There are very few circumstances where charities working in this field can't undertake this kind of activity and make valuable contributions to the maintenance and promotion of human rights. We hope this revision makes it a lot clearer to these organisations how much they can do to promote human rights."
The commission says that its previous guidance was misinterpreted by charities that assumed they were prevented from campaigning in countries that don't have human-rights legislation.
"If anything, there may be even more scope for political campaigning in a country that doesn't have human-rights legislation than in one that does," said a spokeswoman. "In any event, the guidance has been amended to remove a distinction that has proved to be counter-productive."
The guidance also includes a section on political activities by charities.
It says that charities can engage in political activities to further their purposes, but charities with purposes that "involve trying to secure a change in the law, or a shift in government policy, or a reversal of a government decision has (at least in part) political purposes and cannot be a charity".