One of only a handful of Japanese veterans who survived the battle of Iwo Jima – one of the bloodiest campaigns of the Pacific war – spent a recent memorial service on the island alongside US veterans after being told there was no space for him among the Japanese contingent.

The memorial to mark the 70th anniversary of the battle, in which only 1,000 of 20,000 Japanese soldiers survived, was attended by the Japanese defence minister, Gen Nakatani, the families of fallen Japanese soldiers, as well as veterans, relatives and officials from the US.

But Tsuruji Akikusa, the only surviving Japanese veteran to attend the ceremony earlier this month, found himself unable to take his place alongside his compatriots – an apparent snub that caused consternation among US veterans, attendees told the Guardian.

The incident was one of several remembrance events taking place in Japan this year to mark the 70th anniversary of the end of the Pacific war. The prime minister, Shinzo Abe, who has called on Japan to take a less “masochistic” view of its wartime history and honour those who fought for their country, will mark the anniversary of Japan’s defeat on 15 August 1945 with a “forward-looking” statement whose wording will be closely watched by the country’s former enemies.

Akikusa, an 88-year-old former radio operator, was only able to revisit Iwo Jima, located in the Pacific 760 miles (1,220 kilometres) south of Tokyo, after a TV documentary crew agreed to pay for his trip to the island on a US plane.

The Japanese Iwo Jima Association denied any knowledge of the apparent snub. “Mr Akikusa is not a member of the association, which is for bereaved families,” the association’s head, Tetsuro Teramoto, told the Guardian. “In fact, I’ve never met him.”

Teramoto, whose father died in the battle, said the association had been able to take only a limited number of people to the island, which is closed to the public all year except one day.

“There are rules about the numbers because there is only a limited amount of space. The place was full, and there are only a certain number of vehicles available [to drive people around]. Anyone claiming that he was snubbed has been misinformed.”

The Japanese defence ministry said it was not aware of the incident, while the foreign ministry could not be immediately reached for comment.

The incident reportedly puzzled some US veterans – Akikusa’s former adversaries – while witnesses struggled to explain his treatment.

“Japan is willing to make a big show of honouring the dead, but having a survivor at the ceremony may have been an unwanted reminder that this was a major battle that Japan lost,” said one attendee who asked not to be named.

Akikusa, who regards Iwo Jima as his second “hometown”, did not protest but, according to witnesses, was annoyed at being unable sit inside the Japanese tent at the ceremony.

After initially accepting that he would not be able to join the Japanese party because no seat had been prepared for him, Akikusa asked to get close enough to the service to observe the minute’s silence so that he could pay tribute to his fallen comrades.

He discreetly took a seat in the shade among 25 US veterans of Iwo Jima and hundreds of their relatives and friends.

Another attendee told the Guardian: “Americans are treated as heroes when they return from war, but Japanese are treated as heroes when they die in war.”

The battle for control of “Sulphur Island”, whose airfield put US B-29 bombers within striking distance of the Japanese mainland, was one of the most brutal of the Pacific theatre of the second world war.

More than 500 US marines died on the first day of fighting after swarming ashore only to find their progress hindered by the island’s beaches of fine black sand and, once they were ashore, a fierce attack from enemy soldiers concealed in the huge network of bunkers and tunnels carved into Iwo Jima’s volcanic earth.

The arrival of US troops on the summit of Mount Suribachi four days later was the cue for one of the most famous war photographs ever taken – the raising of the Stars and Stripes by six US servicemen, captured by photographer Joe Rosenthal.

Akikusa, who was an 18-year-old radio operator in 1945, recalled how seeing the US invasion force on the morning of 19 February convinced him that Japan’s defeat was inevitable.

“I was overwhelmed,” he told the BBC earlier this month. “How could they have so many ships? There were more than in the entire Japanese navy. It was then I realised we were going to lose the war.”

The battle, which US military leaders thought would last only days and proved the most costly in the marine corps’ history, continued for five weeks.

About 6,800 US soldiers died and 17,000 were injured, while only 1,080 of the 22,000 Japanese troops defending the island survived. Fewer than half of the bodies of the Japanese who died on Iwo Jima have been retrieved, according to Japan’s health ministry.

Akikusa, who is said to be reluctant to discuss the recent memorial incident, was badly injured at the start of the battle and spent weeks trapped inside a cave while his comrades died around him. He wasn’t helped out of the tunnel until the end of April after being discovered, malnourished and barely conscious, by a US marine and his war dog.

“Why wasn’t this survivor, who is testament to the strength of the human spirit, given a seat of honour on the Japanese side?” said another witness, speaking on condition of anonymity.

“The US veterans were baffled. They wondered why he wasn’t sitting with the Japanese families and officials, and even thought he should have made a speech.”

The families of dead Japanese soldiers regard Iwo Jima as sacred ground. Visitors to the island are encouraged not to take home mementoes because they are thought by some to contain the spirits of dead soldiers.

One witness speculated that Akikusa’s presence may have added to the deep sense of loss still felt by the relatives of the dead. “Some of the relatives would have looked at him and thought: ‘Why are you here when my father or brother or husband didn’t make it out alive?’” he said.

