Two Queenslanders arrested after terrorism raids are being prosecuted under laws designed to catch 1970s mercenaries in Africa, an expert says.

Outdated laws are being used to prosecute two Queenslanders for allegedly supporting terrorist groups in Syria, an international law expert says.

The men have faced Brisbane Magistrates Court following raids in Brisbane and Logan this week.

Omar Succarieh, 31, is alleged to have raised money for Syria-based extremist group Jabhat al-Nusra, while Agim Kruezi, 21, is accused of recruiting for the jihadist Islamic State (IS) and obtaining funds to fight in Syria.

They are charged with breaching the Crimes (Foreign Incursion and Recruitment) Act of 1978.

University of Sydney international law professor Ben Saul said the federal law, which was drafted after a royal commission into intelligence and security, was created before Islamic terrorism was a big global security concern.

“The foreign recruitment act was concerned with the rise of mercenaries in places like Africa and decolonisation struggles,” he told AAP on Friday.

He said the law, banning Australians from giving support to non-state militia groups, was also inconsistent with US plans to back moderate rebel groups in Syria, as part of a plan to eliminate IS.

“It suggests the law is out of step with the politics,” Prof Saul said.

Australia is considering how it would join a US-led campaign in Iraq and Syria.

But Prof Saul said giving arms to anti-government rebels was against international law without a UN Security Council resolution.

Australians who engage in terrorist atrocities overseas can be charged under the criminal code.

It was amended in 2002 and 2003, following terrorist attacks in the United States and the Bali bombings.