Two staff members of a Sydney cafe have revealed how they plotted to stab a gunman who held them hostage during a 16-hour siege in December.

Two victims of the deadly siege in Sydney were being remembered at private memorial services, a week after a gunman took them hostage inside a city cafe.

An Australian TV newsreader broke down in tears during a live broadcast when she realised her connection to one of the victims of yesterday's siege at a Sydney cafe.