Mr Blair was speaking at a lunch in honour of Emperor Akihito and his Empress on the third day of a state visit dogged by demonstrations by former prisoners of war.

The state visit aims to strengthen the links between Britain and Japan.

During lunch, Mr Blair drew on good memories he and his wife had of their visit to Japan in January.

He said: "Of course our relations were not always like this. As you said at Tuesday's banquet at Buckingham Palace, many still bear the scars of war.

"For some the scars of the past go so deep they will never heal. We have to understand and appreciate this.

Veterans: promised a meeting with Blair

"My generation in particular has not forgotten what we owe to the generation that went before us. And we never will."

Mr Blair has promised a meeting with labour camp survivors who are campaigning for compensation and an apology from Japan.

The offer was made as veterans and former internees delivered a letter to Downing Street asking Mr Blair for his support and for a meeting.

The two-and-a-half page letter was delivered just before the Japanese Emperor Akihito arrived for lunch with Mr Blair and his wife Cherie.

Arthur Titherington, chairman of the Japanese Labour Camps Survivors Association, said Mr Blair's private secretary had promised a meeting.

He said: "The private secretary said the prime minister was sorry he has been unable to see us, but he has promised there will be a meeting with Mr Blair some time in the next two weeks.

"I will patiently wait. That's all I can do."

Mr Titherington had earlier criticised the Mr Blair for not becoming involved in the PoW's fight.

"The message seems to be getting across to Tony Blair that we have not been treated very well by him and I think he's feeling a bit guilty," said Mr Titherington.

The letter appealed to the prime minister to have the "courage" to consider reopening the issues of compensation and an apology.

The PoWs want Mr Blair to announce that he will work with the Japanese Government to resolve both issues and end "the 53-year history of betrayal" suffered by ex-PoWs.

Kazuo Chiba: imperial couple not humiliated

As the letter was handed in, about 50 former PoWs and internees continued their protest outside Downing Street.

The Emperor's official spokesman, Kazuo Chiba, denied the trip had been a failure of Japanese diplomacy.

He said: "I do not think that Japanese diplomacy tried to buy the hearts and minds of the British media. Since we didn't try to do that there is no failure as such."

He added that the imperial couple had not been humiliated but had taken it all in their stride.

The spokesman said of Mr Blair's Downing Street speech: "He did speak about the fact that we cannot forget. I think he meant the British.