Nigel Farage has been criticised by the widower of murdered MP Jo Cox after he claimed the tragedy in Berlin – and events of a similar nature – will be the “legacy” of Angela Merkel.

The comments came after a migrant was detained over the Berlin incident in which at least 12 people died and 48 were injured when a lorry ploughed into a Christmas market.

Police believe the man, allegedly from Pakistan and named as “Naved B”, arrived in Germany about one year ago, according to local media reports.

But Mr Farage, the former leader of Ukip, was accused of political point scoring after he posted on his Twitter account the day after the attack: “Terrible news in Berlin but no surprise. Events like these will be the Merkel legacy”.

His comments provoked a backlash on social media with Brendan Cox replying: “Blaming politicians for the actions of extremists? That’s a slippery slope Nigel.”

Earlier, in response to the attack, Mr Cox had said “we must pull together to drive out hate in all forms”. He continued: “Far right and extremists share same hate driven psychology, intolerance towards difference and tendency to violence. We must defeat both”.

But in an extraordinary step the former Ukip leader then attacked Mr Cox for his comments. On LBC radio, Mr Farage said: “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.”

“I’m sorry Mr Cox but it is about time people started to take responsibility for what has happened. Mrs Merkel has directly caused a whole number of social and terror problems in Germany. It’s time we confronted that truth.”

Last month, the terrorist Thomas Mair, who repeatedly shot and stabbed Ms Cox during the attack before the EU referendum in June, was sentenced to prison for life. The court had heard how Mair shouted, “This is for Britain” and “Britain First” during the attack.