Indonesian police say that a group of Australian activists who are planning to enter the disputed Papua region by boat will be detained and possibly arrested.

About 30 Australian and West Papuan activists plan to set sail from Cairns tomorrow in three boats, calling themselves the "Freedom Flotilla".

Deputy chief of Papuan police Paulus Waterpauw says unauthorised boat arrivals will be intercepted by the navy and probably detained by immigration authorities.

Mr Waterpauw says anybody in the group who has a criminal record, or is on the country's wanted list, will face arrest.

Indonesian president Susilo Bambang Yudhoyono has also issued a strong warning to other countries, saying they should not violate Indonesia's sovereignty.

Mr Yudhoyono reasserted that the Papuan provinces were an inseparable part of Indonesia.

He says the Papuan provinces are part of Indonesia and that should be respected.

Indonesian foreign minister Marty Natelegawa has dismissed the planned voyage.

"Yet another one of those cheap publicity stunt[s]," he said.

Mr Natelegawa says Indonesia has been in contact with Australia but has not asked it to prevent the boats from leaving.