Australian customs officers fought off knives, machetes and flaming missiles as they apprehended an illegal Indonesian fishing boat, Justice and Customs Minister Chris Ellison said Wednesday.

The Indonesian boat, which was carrying a huge quantity of shark fins, was found late Tuesday in the Arafura Sea north of the Northern Territory.

When it failed to respond to warning shots from navy and customs boats, the Australian vessels gave chase, Ellison said.

The fishermen used long poles set on fire to keep the Australians from taking the vessel, while the crew brandished knives and machetes and threw lead weights and burning missiles at the Australian boarding party.

"After a chase lasting several hours, customs and navy officers managed to overcome these obstacles and take control of the fishing boat and its nine crew," Ellison said.

More than 50 whole sharks and two complete holds full of dried shark fin were found onboard, he added.

Australian officials will investigate the incident "with a view to pursuing the offenders to the full force of Australian law," he said.

"We want to send a clear message that aggression toward our officials on the seas will not be tolerated by Australia, especially within our own territorial waters."

The boat was towed to the northern port of Darwin.

Indonesia fishing boats are regularly picked up in Australian waters.