Sonia Sotomayor has been sworn in as the first Hispanic judge in the US supreme court, the highest judicial body in the United States.

After taking the oath in a ceremony in Washington on Saturday, Sotomayor became only the third female supreme court judge in the court's 220-year history.

It was the second swearing-in of the day for Sotomayor - an earlier, off-camera ceremony was followed by a televised event in a conference room at the supreme court.

Her mother, Celina, and Juan Luis Sotomayor, her brother, stood beside her during the administration of the public oath.

Sotomayor, the first supreme court judge to be appointed by Barack Obama, the US president, is, at 55, the second youngest of the court's members.

Accused of bias

Her nomination was intensely debated, with some Republicans opposed to her appointment arguing that she was biased in favour of Hispanics and that ethnicity and gender could play a role in her judicial decisions.

In some speeches her critics referred to as evidence, Sotomayor said a "wise Latina" might reach a better legal decision than a white man.

Sotomayor said that the comments, made in addresses to women's and Hispanic legal groups, were aimed at motivating young people to enter the legal profession.

Democrats, who have control of the senate, said Sotomayor was the ideal candidate for the nine-member supreme court.

The court has been closely divided with four liberal and five conservative members, and Sotomayor’s appointment as the replacement to Justice David Souter, a liberal who retires from his position this year, kept that balance.