Eighteen months after he was labeled a terrorist and told to stay away, controversial former British MP George Galloway has finally delivered his speech along with a blistering attack on the Canadian government.

Addressing a boisterous crowd of supporters gathered in a downtown church hall Sunday afternoon, Galloway said the only threat he poses is to the career of the man who effectively barred him from Canada last year.

"Jason Kenney, I'm challenging you to a public debate anywhere, anytime, in any venue you choose" Galloway said, offering to stand outside the minister's Calgary constituency office until he gets one.

Galloway, an outspoken anti-war activist, broadcaster and former Labour Party MP, also said he would sue the federal immigration minister for slandering him in front of the world. Branding him a terrorist, Galloway said, caused him "18 months of hell."

"Let me make this clear, I am not, nor have I ever been a terrorist or a supporter of terrorism or any kind of security threat to Canada," he said.

"But I think I am a threat to Jason Kenney's political career, and I intend to continue to be so until he's gone."

In 2009, Galloway was scheduled to travel here for a series of speeches on the wars in Iraq and Afghanistan, of which he has been one of the most vocal opponents. But in the days leading up to his arrival, Ottawa accused him of supporting the militant Palestinian group Hamas, which Canada considers a terrorist organization.

Galloway decided to cancel his trip and his supporters mounted a court challenge of the decision by the federal government and the Canada Border Services Agency that the former MP was a possible security risk.

Last week a judge ruled that the government failed to establish sufficient proof that Galloway is a terrorist, and said the decision to bar him was politically motivated.

"It is clear that the efforts to keep Mr. Galloway out of the country had more to do with antipathy to his political views than with any real concern that he had engaged in terrorism or was a member of a terrorist organization," Justice Richard Mosley wrote in his ruling.

"It's a comprehensive beating that Jason Kenney took in that judgment," Galloway said Sunday, noting the "deafening silence" from the minister's office.

"I hope it's because they learned a valuable lesson: in a democracy it is fatal to be caught telling lies."

Galloway has denied making contributions directly to Hamas, but he does admit donating ambulances, medicine, equipment and salaries for nurses and teachers to the residents of Gaza.

For his part, Kenney is not commenting on the ruling or whether there will be an appeal.

Vowing "to seek redress" Galloway told his supporters that his lawyers are processing papers to make good on his threat to sue. Galloway, who claims the decision to bar him from Canada cost him his seat in the British Parliament, says he has also had to make adjustments in order to protect his and his family's security.

After Galloway's 24-hour stop in Canada, he is heading to Damascus where he plans to join a convoy to Gaza. But he promises to be back in November for a 10-city tour.

"That's five more cities than I originally intended to visit, and I'm sure that the audiences will be at least twice as big," he said.

With files from CTV News and The Canadian Press