Japan's prime minister has vowed to defend disputed remote islands from threats by China after a series of confrontations that have raised the risk of an armed clash.

"The security environment surrounding our country is increasingly becoming more severe as we face provocation to our territorial rights," Prime Minister Shinzo Abe said. "I will take the lead to stand up against the present danger and protect the people's lives and asset, as well as our land, the seas and the air at all costs."

His comments, made in a speech to Japan's Self-Defence Forces in the country's south, apparently referred to China's growing presence near the disputed islands, called Senkaku in Japan and Diaoyu in China.

The uninhabited islands are controlled by Japan but also claimed by China. Japan's nationalisation of the islands in September triggered violent protests across China, hurting Japanese companies there and the economy.

China has sent surveillance ships regularly to waters near the islands, and aircraft from the two sides have trailed each other, raising the risk of missteps that could trigger a clash.

Japan has recently launched diplomatic efforts to ease tensions, with China-friendly officials visiting Beijing for talks.

Mr Abe's government last week endorsed a budget bill for this year that included 4.75 trillion yen (32 billion) in proposed defence spending partly aimed at beefing up Japan's coastal and marine surveillance around islands also claimed by China and Taiwan. The government also plans to beef up coastguard deployment in the area.

Later Saturday, Mr Abe was to visit the regional coastguard office on the southern island of Okinawa, which is in charge of patrolling in the waters around the disputed islands, to meet the officers.

During his Okinawa visit, Mr Abe also met governor Hirokazu Nakaima and promised his effort to speed up the relocation of Marine Corps Air Station Futenma, which Japan and the United States had decided to close more than a decade ago.

The base, located in a heavily populated area of Okinawa, is still in operation because a replacement site has not been readied. The Futenma issue is expected to be among the main topics Mr Abe plans to discuss with President Barack Obama during his planned US trip in February.

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Japan PM vows to defend islands