Jakarta, Sep 10 (DPA) Indonesia warned Thursday that the move by Australian police to open a war crimes investigation into the deaths of five journalists allegedly killed by Indonesian troops in East Timor in 1975 could hurt ties between the two countries.

An Australian coroner's inquiry two years ago concluded the five were deliberately killed by Indonesian soldiers to prevent news of Jakarta's invasion of East Timor from leaking out.

Indonesia has always maintained that the journalists, known as the Balibo Five after the town in which they were killed, died in crossfire between Indonesian soldiers and East Timor fighters.

'It has the potential (to hurt ties) because it serves as a new source of irritants,' Indonesia foreign ministry spokesman Teuku Faizasyah said.

'This is a very serious issue, and we will see where the process will lead,' he said.

Faizasyah ruled out the prospect of Indonesia extraditing its citizens to Australia.

He said the investigation could have an impact on people-to-people relations between the countries.