Donald Trump has stirred controversy again. Days after the horrific Paris attacks, the US presidential candidate called for increased scrutiny and even closure of mosques across the United States if they are found to promote hatred.

Trump said if he were to be elected president, he would raise surveillance of mosques because most of the incitement and planning takes place inside them. "Well, you're going to have to watch and study the mosques because a lot of talk is going on at the mosques. I would hate to do it, but it's something that you're going to have to strongly consider because some of the ideas and some of the hatred, the absolute hatred, is coming from these areas," he told MSNBC in an interview.

The big-mouthed Republican candidate's comments came as a new video emerged in which Isis threatened a strike on Washington, besides other places across the world. Trump also criticised New York Mayor Bill de Blasio's decision last year to end surveillance on Muslims in the city.

The New York Police Department's Demographics Unit, according to an Associated Press report in 2011, had spied on Muslims and mosques around the city with help from the CIA. The group gathered databases on where Muslims lived, shopped, worked and prayed. It also infiltrated Muslim student groups, planted informants in mosques and monitored sermons. After Blasio took over in April last year, the program was scrapped owing to numerous complaints and lawsuits.

Trump also called for a ban on allowing Syrian refugees into the country. Other Republican contenders Marco Rubio and Ben Carson have mirrored Trump's views on the refugees, saying it's impossible to know whether those fleeing Syria have links to Islamic militants.

US President Barack Obama, however, has lashed out at critics of his refugee policy. At a news conference in Turkey, he termed as "un-American" the idea of accepting refugees based on their religion. The US plans to allow as many as 10,000 Syrian refugees into the US.