Sydney siege: Gunman 'requests Islamic State flag'

A gunman is holding staff and customers hostage at a cafe in Sydney, Australia.

The Lindt cafe in the city centre is surrounded by armed police. Officers have made contact with the gunman.

A black Islamic flag has been displayed at the window.

The BBC's security correspondent Frank Gardener says it appears the gunman has "the wrong flag" and has asked for a flag of the Islamic State group.