Four out of 14 drug convicts on death row in Indonesia have been executed by firing squad this morning, despite pleas from their families and advocates.

The executions of an Indonesian man and three Nigerians took place at Nusakambangan island prison in Central Java, where Australians Andrew Chan and Myuran Sukumaran were executed last year.

Authorities say the other 10 on death row will be executed at a later unspecified date, as Indonesia shows no signs of backing down on the death penalty.