Nigel Farage today lost another UKIP election candidate who has quit the party in protest at 'unforgivable racist abuse' from a senior MEP. Tim Wilson rounded on Mr Farage for ignoring the widespread condemnation of Scotland MEP David Coburn, who recently compared a Muslim minister in the Scottish Government to convicted terrorist Abu Hamza. In his resignation letter, Mr Wilson, who was due to stand for UKIP in South Northamptonshire – and was tipped to come second behind the Tories – claimed he has been 'forbidden to speak about Islam favourably' by party bosses. Ukip leader Nigel Farage defended Ukip MEP David Coburn who compared a Muslim minister in the Scottish Government to convicted terrorist Abu Hamza. Ukip candidate Tim Wilson rounded on Mr Farage for ignoring the widespread condemnation of the remark . The move has piled more pressure on Mr Coburn to resign and comes just days after another candidate, Jonathan Stanley, quit in protest at the 'racist filth' in UKIP. Mr Stanley, who was due to stand in the Cumbrian seat of Westmorland and Lonsdale, was the party's former head of policy in Scotland. UKIP has also lost two other General Election candidates in recent days in separate incidents. MEP Janice Atkinson was expelled after her chief of staff was filmed allegedly attempting to make fraudulent expense claims. The party's candidate for Scunthorpe Stephen Howd, was suspended last week following an 'alleged incident at his workplace'. Mr Coburn's recent controversial comment was made during a telephone conversation with the Scottish Daily Mail earlier this month, in which he spoke about his appearance on BBC Two show The Big Immigration Debate. He claimed that SNP Europe and International Development minister Humza Yousaf was supposed to appear on the programme, and said: 'Humza Yousaf, or as I call him, Abu Hamza, didn't seem to turn up.' Ukip's only Scottish MEP David Coburn is facing calls to resign . Mr Coburn has since apologised for the remark and Mr Farage has dismissed it as a 'joke in poor taste', adding today: 'That's David… that's the way he is.' But Mr Wilson told the Mail: 'What Coburn said is unforgiveable - it's racist abuse. It doesn't matter whether it was a private comment, or a public comment, this man has public office and he needs to filter the ridiculous thoughts that come from his brain. 'He should be dismissed from UKIP and held to account.' He added: 'Mr Farage cannot dismiss something like this as a joke. You can't toss this thing off as a joke with a pint of beer. It's unacceptable. 'If a leader cannot understand that it is the effect of his words not his intention that matters then maybe he too needs to consider his position and I would be the first to welcome Mr Farage into the political wilderness.' In his resignation letter to the local party, seen by the Mail, Mr Wilson wrote: 'Since selection, I have been systematically gagged by the party 'whip' and forbidden to speak about Islam favourably… . 'Ironically, while I am told not to talk positively about Islam, a Scottish MEP and member of UKIP has used appalling language that should never be condoned and that must be described as Islamophobic. Mr Farage has dismissed this as a joke. 'This is a red line, therefore, that has been crossed. This is not a joke to me. 'In an interview today, I have criticised both Mr Farage and the Scottish MEP and for that reason, I cannot and will not represent UKIP at an election. 'However, if the party is to progress, it must certainly deal with the thugs and bullies who currently have positions of power and whose appalling views are both tolerated and/or presented as party policy.' Mr Wilson was selected as the party's candidate in February, and joined UKIP last year after leaving the Tories. Earlier today, UKIP leader Mr Farage continued to defend Mr Coburn. He said: 'What's he done wrong apart from telling a joke in poor taste? 'That's David, he's out there, that's the way he is. There was no malintent in it. ‎It was a joke in very poor taste. I wish he would think a bit more before he tells such jokes again.' Nicola Sturgeon arrives at The Scottish Parliament with Humza Yousaf - described by Ukip's David Coburn as Abu Hamza . But Mr Yousaf, MSP for Glasgow, said: 'UKIP's pathetic response to religious hatred, racism and bigotry has exposed them as a party that is so out of touch with people that even their own senior members are abandoning them. 'I welcome Tim Wilson's resignation. He has demonstrated that he is unwilling to be associated with a party that allows Islamophobia to be rife within its ranks. 'Serious accusations have been made about UKIP actively preventing their members talking positively about Islam. Nigel Farage should heed warnings from his own members and demonstrate that he will not tolerate prejudice in any form by expelling David Coburn without any further delay.' A spokesman for UKIP said: 'Tim Wilson was never gagged or told that he could not speak about Islam. 'When Mr Wilson submitted some videos that he intended to use as a viral campaigning tool, all that his regional officers advised him to do was produce shorter videos focused on national issues such as the NHS, not five minutes or more discussing the nuances of Islam in Britain.'
MEP David Coburn's said he called the SNP's Humza Yousaf 'Abu Hamza'
Nigel Farage said the comment was merely a 'joke in poor taste'
Ukip leader rejects cross-party demands to kick the MEP out of the party . Ukip election candidate Tim Wilson rounds on Farage for defending gibe .