Image copyright Jiji Press/AFP/Getty Images Image caption Shinzato was arrested last year by Okinawa police

A US army base worker has been jailed for life for rape and murder in Okinawa, in a case that sparked anti-US protests in Japan.

Kenneth Franklin Shinzato was found guilty of assaulting and killing a 20-year-old local woman last year.

The incident prompted deep outrage among locals and renewed calls for US bases to be removed entirely.

The US maintains thousands of troops on Okinawa on several bases, and locals have long objected to their presence.

Image copyright Reuters Image caption Tens of thousands protested in Okinawa last year against the US military after Shinzato was arrested

Shinzato was a former US Marine who worked as a civilian contractor at the Kadena air base in Okinawa. He was accused of attacking and killing Rina Shimabukuro in April 2016.

He admitted to charges of rape resulting in death and abandoning her body, but denied he had intended to murder her.

Prosecutors said he had repeatedly hit his victim on the head and stabbed her in the neck during the attack.

The court on Friday backed their call for a life sentence for Shinzato.

The case prompted anti-US demonstrations last year in Okinawa and Tokyo. and a formal protest by the Japanese government to the US.

The US has about 26,000 troops spread over several bases on the island, including some in densely populated areas.

The military presence since the end of World War Two has contributed to the local economy, but resentment has built up over the decades with locals complaining of the noise and fearing for their safety, given recent military accidents.

Cases like Shinzato's have also fuelled a perception that US troops and workers pose a danger to locals. In 1995, a high-profile gang rape of a 12-year-old girl by three US service personnel sparked huge protests.

In 2013, two US sailors admitted to raping a woman.

The US and Japanese governments have been trying to relocate part of a large air base to a less populated area of the island, but many Okinawans want it removed altogether.