UKIP have suffered another blow after it emerged that their by-election candidate in Aberdeen is linked to a group that has denounced Islam as a "brutal theocracy".

Otto Inglis has attended meetings of the right-wing Letter Writers' Guild (LWG) – a forum for people of a conservative bent who correspond with the press – which has hit out at the "protection" of minorities and the "Islamic Tsunami that is sweeping onto our shores".

Under the leadership of Nigel Farage, UKIP – which is anti-EU – has recently enjoyed remarkable electoral success south of the Border.

However, the party has never gained a foothold in Scotland, polling less than 1% of the vote at the last Holyrood election.

Farage's hopes of relaunching his Scottish wing ended in chaos on Thursday after a meet-the-press event was hijacked by activists.

The UKIP leader had to be bundled out of the venue with a police escort after protesters accused his party of being "racist Nazi scum".

Hours later, Farage hung up on a BBC Scotland interviewer, after counter-accusing the protesters of being "yobbo, fascist scum".

His party is now facing questions about its choice of Holyrood by-election candidate for the Aberdeen Donside race.

Inglis, a lawyer turned businessman, is pictured on the LWG website at one of the group's meetings.

A section on the LWG website entitled "about us", explains: "We are an informal group of like-minded people, who have come together as the result of becoming known to each other as the writers of regular letters to the press, to express our individual views on the sundry problems that afflict society."

According to its "objectives", the group exists to "jolt politicians of all levels ... out of the complacent quiet lives they lead, and remind them WHO IS THE BOSS!".

Representing what they deem to be the "silent majority", the LWG urges individuals to air their views on "Political Correctness, the £1 million a day fraud of the EU, or the Islamic Tsunami that is sweeping onto our shores".

The LWG also described Islam as: "Not just a religion, but a brutal theocracy. Dedicated to expansion by force. Demanding death for those who either don't want to join, or who want to leave this culturally famished ideology."

On "minorities", the LWG hit out at their "exaltation and protection by our Politically Correct society".The group also claimed that "being a single mother is a good state-funded business".

Speaking to the Sunday Herald, Inglis confirmed he had attended LWG meetings, but said there was "no group" position on any issue.

He said he did not agree Islam was a "brutal theocracy", describing it as a "diverse" religion and adding that he had handled asylum seeker cases for the Refugee Legal Centre.

LWG chairman Malcolm Parkin, who wrote the section on Islam, said the group was "not that formal", and was comprised of "people who have got together over the years".

He said Inglis had been involved with the group for "maybe a year, or a year-and-a-half".

Inglis's LWG link comes after Michael Haseler, UKIP Scotland's new energy spokesman, was revealed to have accused gay people of being "deeply hostile" to heterosexuals.

An SNP spokesman said: "People in Scotland know how extreme and intolerant UKIP are – they also want to abolish the Scottish Parliament – which helps explain why they have never so much as saved a single deposit in any election in Scotland."

UKIP Scotland chairman Mike Scott-Hayward said: "UKIP does not convict people for the opinions of others. If so, nobody would ever talk to one another again for fear of what the press or political opponents might say."