BBC News' Wyre Davies reports from Cardiff

The emperor was subjected to more demonstrations by former prisoners of war as he arrived with his wife at Cardiff Castle.

The protests are set to continue when the emperor visits Downing Street on Thursday.

In a repeat of the scenes in London on Tuesday, former veterans turned their backs in protest as the imperial couple prepared to spend three hours in the Welsh capital, accompanied by the Prince of Wales.

The emperor was cold shouldered for the second day running

On arrival, Emperor Akihito was treated to a 20-minute showcase of Welsh music.

The visit was arranged to mark 25 years of Japanese investment in Wales. There are currently more than 50 Japanese plants in Wales, which have delivered £1.5bn into the local economy since 1973.

There is some hope that the emperor's visit will generate further investment in the Welsh economy.

But former prisoners of war who were held in Japanese labour camps during the 1940s, and subjected to starvation and torture, are continuing to demand a formal apology from Tokyo.

They also want compensation for their suffering.

BBC News' James Robbins reports on the mixed reception given to the Emperor in Wales

As the emperor was visiting Cardiff, the survivors were drafting a letter to the Prime Minister Tony Blair - to be delivered before the Emperor Akihito's Downing Street lunch on Thursday - asking for a meeting.

Arthur Titherington, chairman of the Japanese Labour Camps Survivors Association, said the prime minister had made "glaring errors" that had made protests against the emperor inevitable.

Mr Titherington supported the continued protests in Wales.

Geoffrey Hamilton of the Welsh Development Agency: "We can never have too much Japanese investment"

He said: "I don't entirely agree with the booing, but it is good that these protests are taking place in Wales where there is so much Japanese industry.

"It brings it home that this issue will not go away until our government and the Japanese authorities deal with it properly."

More protesters are expected at Downing Street on Thursday when the emperor arrives, he said.

The royal party was treated to a taste of Welsh culture

Mr Titherington said: "I will be there in the hope that we can hand our letter in before the emperor gets there. We decided today that we should write a letter to Mr Blair himself, though we haven't started drafting it yet.

"The purpose of a letter is to ask for a meeting. We have asked and asked and asked Mr Blair for a meeting, but we haven't got anywhere.

"Mr Blair has made glaring errors. A number of people are telling us that they are angry at the way he has treated us."

At a state banquet on Tuesday evening, the emperor said he could "never forget" the many kinds of suffering undergone by so many in the war.

Members of the local Japanese community cheered the emperor

The emperor's press spokesman Kazuo Chiba went further in an interview with the BBC.

He made his own apology for the actions of some Japanese troops towards British prisoners.

"Those individuals who engaged in such acts ... it was beastly. I am very sorry about it," he said.