A new poll has revealed that two thirds of the UK public believes people who have been adopted should be allowed to inherit the throne.

A national newspaper announced it was launching a legal challenge against one of the central tenets of the hereditary British monarchy.

The Guardian will contest the Act of Settlement which bars non-Protestants, particularly Catholics, adopted children and people born to unmarried parents from succeeding to the throne.

The legal action comes alongside a new poll which shows 66 per cent of people think the ban on Catholic succession should be lifted, while 63 per cent disapprove of the ban on children to unmarried parents, and 68 per cent on adopted children.

Geoffrey Robertson QC will spearhead the case for the paper, which argues that the act contravene human rights laws.

The court will be asked to reinterpret the 1701 law, which the Guardian says also discriminates against women by favouring male succession.

Parliament would theoretically face condemnation from the European Court of Human Rights should it issue a "declaration of incompatibility" and refuse the changes.

The paper will also argue that the Treason Felony Act - forbidding the publication of incitements to republicanism - contravenes Article 10 of the European Convention, which guarantees the right to free speech.

The paper's ICM poll of 1,003 people also shows that 60 per cent of people would prefer to be citizens than royal subjects and nearly a third think there should be a referendum on the next head of state.

Guardian editor Alan Rusbridger said: "Since MPs are barred from openly debating the role of the monarch we thought a newspaper might set the ball rolling."