Despite his frequent descriptions of his Christian faith and taking oath of office on Abraham Lincoln bible, around a quarter of people in the US believed a rumour that President Barack Obama is a Muslim.

A new study by Ohio State University has revealed that nearly 91 per cent of respondents said in a survey, following Obama's November 4 election, they heard the false rumour that he was a Muslim, while 22 per cent claimed they believed it.

What's more shocking is that some 59 per cent of the respondents had heard the rumour that Obama did not qualify to be US President as he was not a citizen by birth, though only ten per cent of them actually believed it.

And, 41 per cent heard that the bulk of donations to the Obama campaign came from "a handful of wealthy foreign financiers" and 20 per cent of them believed it, the study, led by Kelly Garrett, has found.

Obama was sworn in as the first black President on January 20 at a 150-million-dollar extravaganza watched by some two million people with a blunt message to terrorists all over the world -- "we will defeat you".

Climaxing the unlikeliest of journeys to the White House, the 47-year-old African-American was administered the oath of office by Chief Justice John G Roberts Jr, 12 minutes behind schedule, on the steps of the West Front of the Capitol Hill where the US Congress sits.

The huge crowd from across America and many from outside lapped up every idea that the charismatic Democrat propounded in his tryst with history during his 20-minute address after he took oath on the Lincoln Bible.