The number of Muslims living in the United States will double within a generation, according to new research.

According to Pew Research, there are currently about 3.3 million Muslims in the US, making up one per cent of the population. The number is expected to grow to more than eight million by 2050.

Just over half the projected growth is due to immigration but Muslims also tend to have more children than other religious groups.

Donald Trump, front-runner for the Republican party's presidential nomination, has called for all Muslims to be barred from entering the US. 

The number of Muslims in the US at present compares to 5.7 million Jews and 2.1 million Hindus. In some cities, Muslims now make up more than one per cent of the population. States such as New Jersey have two or three times as many Muslims as the national average.

Unlike the UK, where the last two national census questionnaires have included a question about religion, the US Census Bureau does not ask about religion so any calculation of religious affiliation by number has a degree of estimation in it.

Pew Research said: "Since our first estimate of the size of the Muslim American population in 2007, we have seen a steady growth in both the number of Muslims in the US and the percentage of the US population that is Muslim.

"In addition, our projections suggest the US Muslim population will grow faster than the Hindu population and much faster than the Jewish population in the coming decades. Indeed, even before 2040, Muslims are projected to become the second-largest religious group in the US, after Christians. By 2050, the American Muslim population is projected to reach 8.1 million people, or 2.1 per cent of the total population."