But the strong message of condemnation and unity from police, politicians and the city's Muslim leader came even as some followers of a controversial right-wing group were apparently rejoicing in the fire that severely damaged the mosque overnight.

Police Minister Jo-Ann Miller said the state government was "totally disgusted" with the attack.

"This has got to stop," she said.

"We cannot as a community afford to have people who are running around thinking it's OK to upset people who are legitimately going about their business at a place of worship.

"We have come a long way in Australia. We've come a long long way in Queensland and in Toowoomba and we will not tolerate this anymore."

Her comments were echoed by LNP member for Toowoomba South John McVeigh and Toowoomba Mayor Paul Antonio.

Cr Antonio admitted the suspected attack on his city's mosque was particularly disappointing given the effort the community had put into building harmony after an arson attack in January.

"It is disappointing but in our society we have a wide range of thoughts and behaviours and sadly this is the bottom of the trough and that's what we're seeing here today," he said.

Toowoomba's Muslim community has refused to be bowed by the fire, which the state's lead Islamic spokesman said "almost completely destroyed" the place of worship.

The Toowoomba International Food Festival, which was to be held at the mosque, will still go ahead on Sunday.

Islamic Society of Toowoomba founding president Professor Shahjahan Khan said he valued the support given by people from other religions and organisations.

He said the community must "go along with life" and rebuild the mosque.

"For the person or persons who have done this, we have nothing against you," he said,

"We haven't done anything wrong to you and please realise what you have done is not good for yourself, is not good for the city that you live in and the city we are so proud of."

But commenters posted gloating comments after the Reclaim Australia Facebook page shared a news article about the fire.

"Just another 'False Flag' to make themselves look like the victims of hate crimes," one man wrote.

Another went so far as to congratulate those responsible: "Who ever (sic) lit it up is a champion."

"Damn I'm all out of marshmallows," another said.

The group hit the headlines earlier this year after holding nationwide - and at times violent - rallies against "sharia law, halal tax and Islamisation".

Police are calling for anyone with information about the fire or who might have seen anything suspicious near the West Street mosque between midnight and 2am Friday to call Crime Stoppers on 1800 333 000.

Darling Downs District Officer Acting Superintendent Ben Marcus said CCTV would play a "critical part" in the police investigation.

He refused to say if a link to the January fire had been ruled in or out, saying it was an "obvious line of inquiry".

Police have been conducting nightly patrols at the mosque since last year, he said.

Professor Khan said he didn't know of anyone threatening the mosque in the lead-up to the fire.