HENRY McLeish has insisted that Scottish football has to shed its "darker side" of sectarianism and pro-terrorist chanting or else it will never attract new supporters.

The man commissioned by the SFA to carry out an independent review of the game claimed that in a general sense there had been major progress in the six months since he unveiled his findings, but sectarian and illicit chanting were still embarrassments which had to be wiped out.

The former first minister supports the Offensive Behaviour at Football and Threatening Communications Bill which is currently at an extended consultation phase at Holyrood. The bill aims to criminalise offensive and threatening chants heard inside grounds or from those travelling to or from games or watching in pubs or at outdoor screenings. Some supporters have criticised the proposed legislation as an attack on freedom of speech.

"We are blessed that we have free speech," McLeish said. "But there's a distinction between free speech and behaviour regarded as intimidating, sometimes irritating and, in the laws of the land, illegal. If you love the game with the passion I do you've got to own up to the fact there are aspects of the game that have no place in a modern Scotland or in football.

"If we want to have a game which is attractive to more than just the core fanbase – to women, children, young people and those who have never been – then there is a darker side to Scottish football we have get rid of. I make no apologies for that. The clubs are not entirely responsible. Sectarianism is an issue for Scotland which is manifest in football grounds.

"It's not just a matter of blaming Rangers or Celtic. But along with the two big clubs, the other clubs, the SFA and SPL, we have to show the outside world we mean business. We have to be tough. We know if we want this kind of warmer, friendlier game then we need to tackle these excesses. And in that case Alex Salmond is right: this is an embarrassment to Scotland. I applaud the legislation because this is besmirching the reputation of Scotland.

"I care passionately about how the country is viewed by people who don't play football and by people outwith the country who may or may not be interested in the game. That's why it's important that the government gets this done and dusted. Then it's over to the authorities, the police and others, to implement it."

The Joint Action Group on sectarianism, set up by the Scottish Government, met this week and it was subsequently announced that clubs whose fans sing terrorist chants could be fined, lose points or be made to play behind closed doors if they are not tackling the issue. Clubs will vote soon on amending their unacceptable conduct rules. The rule change would penalise songs, chants and behaviour referring to terrorist organisations.

McLeish said the football authorities, long seen as weak on sectarianism or chants about terrorism, are becoming more firm. "The game up to now has been very insular, very exclusive, very football, very 'we know what we should be doing'. But football is more important than that. I think the authorities are changing."