WASHINGTON, Dec 3: The first US Muslim lawmaker, Congressman-elect Keith Ellison, will take his oath of office on the Holy Quran and not on the Bible.

Although some have criticised the decision, the Minnesota Democrat says that the US Constitution gives him the right to use the Muslim holy book, and that is what he intends to do on Jan 4.

"Using the Holy Quran, really to me, is an affirmation of the religious freedom and diversity that the Constitution stands for,” Mr Ellison said.

His campaign manager Dave Colling said that while Mr Ellison will be the first Congressman to use the Holy Quran, "most members do not even take an individual oath with any book.”

Eugene Volokh, a professor of law at the University of California, Los Angeles, says that the Constitution authorises people not to swear their oath at all, protecting atheists and agnostics.“Why Muslims and others would not be equally protected?” he wrote for National Review Online.

Members of Congress are sworn en masse in the chamber, and no Bible or other religious document is used for the oath. However, several incoming members use Bible for their individual swearing-in.

Some conservative organisations have criticised his decision. Dennis Prager, a conservative radio host, says that even if the Constitution allows him to take an oath on the Holy Quran, he should adhere to the historical tradition of taking the oath of office on the Bible.