Medellin: Australia's consulate in Bogota is making urgent inquiries to establish whether any Australians were on board when a Colombian tourist ferry packed with 150 passengers sank.

Authorities have said at least nine people are dead and 30 are missing after the ferry capsized on a reservoir near the city of Medellin on Sunday local time.

A major rescue effort involving Colombia's air force and firefighters from nearby cities is looking for survivors at the Guatape reservoir where the accident took place. Medellin's mayor has appealed to motorists to stay off roads to facilitate the arrival of rescuers, ambulances and first responders.

"The most important thing right now is to save lives," said mayor Federico Gutierrez.

Dramatic videos circulating on social media show the party boat, El Almirante, rocking back and forth as people crawled down from a fourth-floor roof as it began sinking.

A flotilla of recreational boats and jet skis rushed to the scene to pull people from the vessel and deliver them to the shore, avoiding an even deadlier tragedy.

It's unclear what caused the boat to sink, but survivors told local media that it appeared to be overloaded and none of the passengers on board were wearing life vests.

General Jorge Nieto, the head of Colombia's police, said 24 people were being treated for injuries at a local hospital.

A spokesperson for the Australian Department of Foreign Affairs and Trade said: "The Australian consulate-general in Bogota is making urgent enquiries to determine whether any Australians have been affected by the sinking of a vessel on Gautape reservoir in Colombia.

"If you have any concerns for the welfare of family and friends in the region, you should attempt to contact them directly. If you are unable to contact them and still hold concerns for their welfare, you should call the Department of Foreign Affairs and Trade's 24-hour consular emergency centre on 1 300 555 135, or +61 2 6261 3305 (if calling from overseas)."

AP, Fairfax Media