Six Australians are about to be placed on Interpol's most wanted list as diplomatic tension mounts over a formal demand that they return to Peru to stand trial for murder.

Sydney university students Sam Smith, Harrison Geier and Andrew Pilat, and Melbourne trio Hugh and Tom Hanlon and Jessica Vo have been named as prime suspects in a homicide case that centres on the mysterious death of a hotel doorman in the Peruvian capital of Lima.

Facing a nightmare and diplomatic row: (From left) Hugh Hanlon, Sam Smith, Tom Hanlon, Andrew Pilat, Jessica Vo and Harrison Geier. Credit:Dallas Kilponen

Police allege that in January last year, the tourists killed Lino Rodriguez Vilchez by pushing him off the 15th floor of a building in which they were staying.

Fairfax Media can reveal that, 18 months on, Foreign Affairs Minister Bob Carr and federal Attorney-General Mark Dreyfus were forced to hold crisis talks last week with members of the group and their families. The emergency meetings were triggered by an extraordinary ultimatum from the Peruvian authorities who have subpoenaed all six to return by July 1 to give statements before their trial or be listed as international fugitives under an Interpol red notice.