Prime Minister Shinzo Abe vowed Saturday to defend Japan against "provocations" as he toured the southern region of Okinawa near islands at the centre of a boiling territorial dispute with China.

His comments came in the same week that his government approved a rise in defence spending for the first time in over a decade, explicitly aimed at beefing up defence of the contested island chain in the East China Sea.

"The security environment surrounding our country is increasingly tense," he told some 700 troops gathered at a Japanese airbase in Naha on the main Okinawan island, according to television footage and media reports.

"Provocations are continuing against our country's inherent territorial land, air and sea as well as its sovereignty," he said in an apparent reference to China.

"I am determined to stand at the forefront of you all and stand up against the crisis that is there and resolutely protect at all costs our people's lives and assets as well as our country's territorial land, air and sea."

Chinese government ships have routinely circled the Tokyo-administered Senkaku islands, which China claims and calls the Diaoyus, since September when Tokyo nationalised some of the chain in the East China Sea.

Chinese planes have also sporadically breached the airspace over them, stoking a long-running sovereignty row.

Abe, a hawk who took power for a second time in December when his conservative party scored an election landslide, also said his government would beef up defence in the Okinawan region.

Japan considers the Senkakus as a part of Okinawa.

"We will be steadfast in improving the capacity of the Self-Defense Forces, including reinforcements in the southwest region (Okinawa)," he said.

Japan's already well-equipped coastguard said on Tuesday it would create a special unit over three years with 10 new large patrol boats, two helicopter carriers and a 600-strong force to oversee the East China Sea.

Also this week, Abe said on Friday he intended to release a new statement on Japan's attitude to World War II, a day after unveiling plans to revamp the US-imposed pacifist constitution.

The nationalist premier, who swept to power on promises of a more robust diplomacy that will stand up to China, has long been known to favour the toning down of a 1995 apology for wartime aggression directed at Asian neighbours.

At the same time, he has reached out, saying this week he wanted a summit meeting with Chinese leaders to help improve ties with Beijing.