The widower of murdered MP Jo Cox has hit out at Nigel Farage on Twitter over the former Ukip leader's response to the suspected terrorist attack in Berlin.

Brendan Cox warned Mr Farage was heading for a "slippery slope" after the right-wing politician linked the carnage in the German capital with Chancellor Angela Merkel's policies.

But Mr Farage doubled down when he appeared on radio on Tuesday morning, saying Mr Cox "would know more about extremists than me".

Read more: Berlin 'terror attack' - Man found shot dead in lorry as 23-year-old arrested

Mr Farage had taken to social media in the wake of the outrage, which left at least 12 dead at a Christmas market, saying: "Terrible news from Berlin but no surprise. Events like these will be the Merkel legacy."

The comment prompted hundreds of retweets and replies, including from Mr Cox, whose Labour MP wife was shot and stabbed to death by neo-Nazi Thomas Mair days before June's EU referendum.

Mr Cox wrote: "Blaming politicians for the actions of extremists? That's a slippery slope Nigel."

However, Mr Farage, who led Ukip until November, defended his comments on radio station LBC, saying: "Well of course he would know more about extremists than me, Mr Cox, he backs organisations like Hope Not Hate, who masquerade as being lovely and peaceful but actually pursue violent and very undemocratic means.

Read more: Berlin 'terror attack' - Man found shot dead in lorry as 23-year-old arrested

"And I'm sorry Mr Cox, it is time people started to take responsibility for what's happened. Mrs Merkel had directly caused a whole number of social and terrorist problems in Germany, it's about time we confronted that truth."

Before Mr Farage's Twitter comment, Mr Cox had tweeted: "Terrible news from Berlin. We must pull together to drive out hate in all its forms.

"Far right & Islamist extremists share same hate driven psychology, intolerance towards difference & tendency to violence. We must defeat both."

Mrs Merkel has shifted her policy towards refugees and migrants to the right in recent weeks, including a speech in which she suggested stemming the number entering Germany and restricting the use of face veils.

Germany admitted almost 900,000 migrants in 2015 after deciding to allow in those who had made it to Hungary.

Read more: Berlin 'terror attack' - Man found shot dead in lorry as 23-year-old arrested

Although the numbers had dropped sharply in 2016, Mrs Merkel's CDU party has suffered internal strife and a string of poor election results.

Mair, who killed 41-year-old mother-of-two Mrs Cox as she arrived to hold a surgery in her Batley and Spen constituency in Yorkshire, was handed a whole life sentence in November.

Mair, 53, shouted "Britain first" as he fired three shots at Remain campaigner Mrs Cox and stabbed her 15 times on the afternoon of June 16.

After Mair was jailed, Mr Cox said he had committed the "most incompetent and self-defeating" act of terrorism.