Donald Trump renews war of words with Sadiq Khan

The feud between US president Donald Trump and London's first Muslim mayor Sadiq Khan refuses to die down.

Trump kickstarted his four-day trip to Britain by taking a shot at Khan saying he has done a "very bad job on terrorism." Trump linked terrorism to immigration and said increased immigration was behind deadly attacks across Europe.

"I think allowing millions and millions of people to come into Europe is very, very sad," Trump told the Sun in an interview.

"You have a mayor who has done a terrible job in London. He has done a terrible job," Trump was quoted as saying. "Take a look at the terrorism that is taking place. Look at what is going on in London. I think he has done a very bad job on terrorism."

Calling Trump's comments "preposterous" Khan said terrorism was a global problem that affected other European countries as well.

“What is interesting is Trump is not criticising mayors of those cities, but he is criticising me,” Khan told BBC radio.

“There has been an increase in violent crime across England and Wales... it's gone up by more than 20 per cent... and by four per cent in London... We must deal with the causes but also enforcement and where we have lost £7m in our budget in London I have invested £4m... [but] the idea to blame immigration from Africa is preposterous and we should call him out when does," Khan said.

Khan, son of immigrants from Pakistan, became the mayor of London in May 2016. His feud can be traced back to much before Trump became the president of the US in November 2016. Their war of words erupted shortly after Trump proposed a travel ban on people from certain Muslim countries. However, Trump at the time said Khan would be exempted from the ban.

Responding to Trump's remarks that he would be an exemption, Khan told BBC: “I think Donald Trump has ignorant views about Islam. It’s not just about me. … It’s about my friends, family, and others, from all around the world … and my concern is he’s playing into the hands of extremists who say it’s not compatible to be Western and mainstream Muslim.”