A close adviser to Scotland’s First Minister, Alex Salmond, has been accused of being an Islamist in a report by the Quilliam Foundation, a London-based counter-extremism think tank.

Osama Saeed was unveiled last Friday as the Scottish National Party’s (SNP) candidate for Glasgow Central at the party’s spring conference.

Mr Saeed, an SNP activist who was formerly employed by Alex Salmond, also acted between 2002 and 2007 as a spokesman for the Muslim Association of Britain (MAB), which the Quilliam Foundation describes as being the “front group for the Muslim Brotherhood, the world’s largest Islamist movement”.

Mr Saeed described the report as “politically motivated and utterly disreputable”.

The Glasgow-born 29-year-old has courted controversy in the past after calling for the reintroduction of the caliphate (pan-Islamic leadership) and advocating separate Islamic schools in Scotland.

The Quilliam report — which Mr Saeed dismissed as “a politically motivated smear and utterly disreputable” — asks him to clarify his views on the hudood punishments of Sharia law such as stoning and flogging, and on the freedom to change religion.

It also claims that the Scottish Islamic Foundation, founded by Mr Saeed in 2008 and which has received £400,000 from the Scottish government, provides “a platform for a wide-range of high-profile Islamists” including Kemal Helbawy, founder of the MAB and Alamin Belhaj, the head of the Libyan Muslim Brotherhood.

An SNP spokesperson, describing the Quilliam Foundation as having “zero credibility”, said: “This disgraceful attack is untrue from start to finish.

“Ed Husain [of the Quilliam Foundation] is a self-confessed former extremist and a Labour Party member, and this smear must be seen in the context for what it is. The last thing we need is people with no knowledge of Scotland spreading nastiness and smears.”

But Mr Husain, who was one of the report’s authors, refuted claims that the Quilliam Foundation was operating a smear campaign.

“I’m not involved with the Labour Party and have no personal agenda,” said Mr Husain.

“It’s clear that the Scottish Islamic Foundation is the Scottish version of the MAB and we have solid evidence to back up our claims in the report. We are alerting a wider society to an Islamist entering Westminster.”