At least four people have reportedly been killed and 27 others injured after police allegedly fired on protesting coffee growers in Indonesia's eastern island of Flores.

The AFP newsagency quotes a doctor at a hospital in Ruteng as saying the victims were brought in after staging a protest outside a police station in the town.

A provincial police chief has confirmed that three people were killed after police first fired warning shots when the crowd broke windows at the police station.

The AFP news agency quotes a witness as saying the protest outside the police station followed the arrest of seven men from Pocorankaka district.

The witness told local radio the seven were detained after they tried to re-enter an area in Pocoranaka which had been declared off-limits by local authorities.

The area, formerly a forest, had allegedly been illegally cleared by farmers to plant coffee.