Police say the man believed responsible for the explosion at the ACL headquarters in Canberra wasn’t religiously or politically motivated.

They are waiting to speak further with the 35-year-old man, who is in a Canberra hospital in a critical condition.

“As a result of our conversations with the man, we have been able to establish that his actions were not politically, religiously or ideologically motivated,” ACT Chief Police Officer Mark Walters said.

"Police were able to establish the man’s actions were not politically, religiously or ideologically motivated." @ACTPolicing pic.twitter.com/u6BDs0ZQzg — David Sharaz (@DavidSharaz) December 21, 2016

The man had apparently ignited gas cylinders in the van, setting it on fire, and then walking to hospital late last night.

“Our investigations into this incident are ongoing. Part of those investigations will be to understand the motivation,” Commander Walters said.

Earlier this morning, the head of the controversial lobby said the explosion was designed to intimidate his group.

“Obviously, someone doesn’t like our work and wanted to send a message to us,” ACL managing director Lyle Shelton told reporters at the site of the fire.

0:00 00:00 / 00:00 Share Share on Twitter

Share on Facebook

“We have received multiple death threats and threats of violence.”

The group has been staunch in its opposition to legalising same-sex marriage and the Safe Schools program.

The 35-year-old male involved in the explosion at the Australian Christian Lobby has been transferred to Sydney hospital. @SBSNews — David Sharaz (@DavidSharaz) December 22, 2016

“This has all the marks of an act of political terror,” conservative Queensland politician George Christensen wrote on Facebook.

“I really hope it's not but if it is this should be denounced by all political quarters.”

At the site of the explosion in Deakin, only a few kilometres from Parliament House, windows had been blown out of the building, interiors damaged and concrete scorched by the heat of the explosion.