Japanese Prime Minister Yukio Hatoyama today apologised for breaking his election pledge to move an unpopular US military base off Okinawa, also receiving a public dressing-down from local officials.

Hatoyama's initial plan had caused friction with close ally Washington and his perceived dithering on the issue since - followed by his U-turn - has badly hurt his approval ratings.

During his visit to the southern island Sunday Hatoyama faced angry protests by residents who had hoped to see the US Marine Corps' Futenma Air Station moved entirely off Okinawa, instead of relocated to a less built-up part.

Okinawa, which hosts more than half the 47,000 US troops in Japan, has long sought to remove the bases, which are locally unpopular mainly because of noise, pollution and the risk of accidents and crimes.

"I apologise to people in Okinawa as I could not keep to my word that I'll relocate the base off the prefecture," Hatoyama said in a meeting with Okinawa governor Hirokazu Nakaima, shown on television.

"After holding a number of talks within Japan and with the United States, I reached the conclusion that I have to ask Okinawans about relocating the Futenma base within Okinawa -- specifically speaking, in the Henoko district," Hatoyama told Nakaima, referring to a quiet coastal area of the island.

A grim-faced governor replied: "I cannot help but say that the plan of relocating to Henoko is very regrettable and very difficult."

Hundreds of people protested outside the prefecture building, holding banners saying "We are angry" and some chanting "Hatoyama go home!"

Relations between Japan and the United States have been strained since the centre-left premier took power last September after a landslide poll victory, pledging to move the base off Okinawa, scrapping a 2006 deal between the previous conservative government and Washington.

But the embattled premier earlier this month backtracked on that pledge and stuck with the agreement to find another location for the base on the island, specifically, the district of Henoko.

A settlement to the row

His government and the United States are expected to announce a settlement to the row at the end of this month.

The administration of US President Barack Obama had urged Hatoyama to stay with the original pact, arguing a strong US military presence is crucial for the defence of Japan and stability in the wider Asia-Pacific region.

Hatoyama told the Okinawa governor: "As the prime minister, I have to say that I can't allow the deterrent power of the US forces in Japan, including the Marine Corps, to decline, given that the security environment in East Asia remains fragile."

His comments came after US Secretary of State Hillary Clinton and her Japanese counterpart Katsuya Okada condemned North Korea Friday after a multinational panel blamed it for a deadly torpedo attack on a South Korean warship.

Hatoyama also faced criticism from the mayor of Nago city, which covers Henoko.

"I am absolutely against the plan. I feel extremely regrettable as you betrayed our citizens' trust," Mayor Susumu Inamine told Hatoyama.

Last month, nearly 100,000 protesters attended a rally on Okinawa to demonstrate against the US air base.

And last Sunday, thousands of people formed a human chain surrounding the Futenma facility, located in the urban area of Ginowan, to demand its closure.

Defence Minister Toshimi Kitazawa will discuss the issue with US Defence Secretary Robert Gates on Tuesday in Washington, Jiji Press reported.