TOKYO: Tens of thousands of demonstrators have gathered on the Japanese island of Okinawa to protest against the heavy US military presence there.

The protestors are angry after a former US Marine employed as a civilian worker was arrested over the rape and murder of a local 20-year-old woman.

The case has intensified longstanding opposition to the military bases, spurring calls for US military personnel to be moved off the island.

There are 26,000 US troops on Okinawa.

They work and live on bases that cover a fifth of the island and are a key part of the US-Japan security alliance.

The demonstration on Sunday began with a moment of silence for Rina Shimabukuro, the murder victim, and a message from her father.

"Why my daughter, why was she killed?" said the message, read on his behalf. "My thoughts are the same as those of all the bereaved families that have met with suffering up to now."

A 32-year-old US civilian working at the base was arrested last month in connection with the murder of Shimabukuro.