Hope turned to anguish for red-shirted crowds in Seoul and Tokyo as North Korea's first World Cup finals campaign in 44 years ended in humiliation - but the dream of Korean unity won out among some fans.

Portugal's 7-0 rout of the team from the isolated North drew millions of South Korean viewers Monday night with a quarter of the total TV audience tuning in, according to AGB Nielsen Media Research.

But north of the border, when the scoreline widened to 4-0, the football expert with Pyongyang's Korean Central TV stopped commentating and the broadcast ended immediately after the final whistle, monitors in Seoul said.

A pro-Pyongyang newspaper in Japan described residents of the North Korean capital as hugely disappointed by the loss.

Choson Sinbo said emotions of viewers quickly went from "anticipation and excitement to frustration and disappointment".

"High expectations only bred huge disappointments," its report said. "After watching the opponent's great skill with their own eyes, they were at a loss for words."

Despite Pyongyang's recent threat to turn Seoul into a "sea of flame", some 1,000 people rallied at the Bong Eun Sa Buddhist temple in the South Korean capital to cheer on the communist nation's side.

They chanted players' names, shouted "One Korea!" and waved "unification" flags, a blue silhouette of the entire peninsula on a white background.

"We are dreaming of a day when (the North's striker) Jung Tae-Se scores on a cross from (the South's) Park Ji-Sung. When that day comes, Korea will be unified," the head monk, Myungjin, told journalists.

But supporters were soon exhaling collective groans as North Korea wilted under a barrage of second-half goals from Cristiano Ronaldo's Portugal.

Some spectators sitting in the temple parking lot beat the ground with their fists.

"Before the break, it looked like the North might triumph. Then my heart sank as North Korea began crumbling," Kim Yong-Woo said on YTN TV. "This is because we are one people."

Some Internet users expressed reservations about cheering for the North when memories of the March sinking of a South Korean warship, the Cheonan, with the loss of 46 lives are still vivid.

Tensions are high on the Korean peninsula after the South accused its neighbour of torpedoing the warship and announced reprisals.

"You must restrain yourselves from cheering on North Korea, considering the agonised feelings of the relatives of the Cheonan victims," one user wrote.

But another user said sport and politics must be kept separate.

"Supporting the North Korean football team does not mean supporting North Korea's regime or praising its wrong behaviour."

North Koreans had reportedly been united in cheering South Korea's win over Greece in their opening World Cup match.

Encouraged by a fighting performance against Brazil last week, North Korea showed the Portugal match live on TV. But the drubbing was all too much for the Korean Central TV summariser, who was left speechless.

North Korea now have no chance of progressing to the later stages in South Africa, unlike their stunning run to the quarter-finals in 1966.

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