Image copyright EPA Image caption The arrest comes days after a protest against plans to relocate a Marine Corps base on Okinawa, part of long-running local opposition to the US presence

Japanese Prime Minister Shinzo Abe has expressed his anger after a US military worker in Okinawa was arrested on suspicion of dumping a woman's body.

The body of the 20-year-old woman, missing since April, was found at a location given by the 32-year old man.

Police say the man admitted abandoning the body. They also suspect he killed her but have not charged him with this.

The case is likely to fuel discontent in Okinawa over the large US military presence and crimes by personnel.

It also comes a week before US President Barack Obama visits Japan for a G7 summit.

Image copyright AFP Image caption The US Ambassador to Japan, Caroline Kennedy, was summoned to Japan's Foreign Ministry for a formal protest

Police say the man, Kenneth Franklin Shinzato, was a contractor at the US Kadena Air Base.

Mr Abe told reporters on Friday: "I feel strong anger. I have no words to express, considering how the family feels.

"We urge the US side to take thorough measures to prevent the recurrence of such events."

Foreign Minister Fumio Kishida also summoned US ambassador Caroline Kennedy to formally protest.

"I told her an incident like this is inexcusable and that I feel strong indignation," Mr Kishida told reporters:

Ms Kennedy said the US would "co-operate fully with Okinawan police and the Japanese government, and we will double our efforts to make sure this will never happen again".

But Kenichiro Sasae, Japan's ambassador to the US, said the "tragic event should not overshadow the fundamental objective of the alliance".

The US currently has about 50,000 military personnel in Japan as part of the post-war security arrangement - about half of them are based in Okinawa.

Image copyright Reuters Image caption Amid tension with Beijing over disputed islands in the East China Sea, Japan recently opened another of its own bases in Okinawa prefecture, on Yonaguni Island

Mr Abe recently agreed to suspend construction work required to relocate a US Marine Corps base from one part of the island to another, after years of opposition by locals.

Many locals want the base removed entirely - they believe the relocation will damage the environment and associate US bases with accidents and crime.