By Jack Kim

SEOUL, March 27 (Reuters) - Jong Won-yong, 74, spoke by video link on Tuesday to his three sisters across the border in South Korea for the first time in 50 years and told them: "I thought you were dead."

It marked the resumption -- though without physical contact -- of family reunions on the divided peninsula, broken off last year after the North's missile and nuclear tests drove it deeper into international isolation.

They follow North Korea's breakthrough deal with regional powers last month to end its nuclear programme, setting the stage for improved ties.

"I had no idea you were alive," said Jong who, like most North Korean adults, wore a lapel badge with the image of Kim Il-sung, founder of the reclusive state now run by his son.

Sitting in a studio in Pyongyang, his eyes red and welling with tears, Jong stared into the camera as his sisters in Seoul gave him a who's who of their extended family in the South.

When talk touched on their dead parents, the sisters suddenly grew sombre, weeping as they spoke of how their father died of a stroke in Seoul three years ago.

Still technically at war, it was only seven years ago that the two Koreas agreed to the reunions of families broken apart in the chaos of the 1950-53 Korean War.

The Jong family was one of 120 being reunited by video link over the next three days, the first reunions for almost a year.

In a sign of how complex relations between the two remain, no sooner had Seoul begun shipment of food and fertiliser aid to the North this week than military intelligence demanded dozens of pro-North Web sites be blocked in the South.

"We don't ban Web sites simply because they are pro-North," Kim Chul-whan, an official at the Information Ministry's Internet safety commission, told Reuters.

"We ban Web sites that praise the North Korean government and leaders Kim Il-sung and Kim Jong-il, admire the North Korean Workers' Party, quote or refer to North Korean propaganda or speak of 'juche' (its doctrine of self-reliance)."

Asked where they live, the sisters flashed a card on the screen with address and telephone number -- a largely pointless gesture since private mail or telephone contact is still banned across the heavily militarised border, the last Cold War frontier.

Han Wan-sang, head of South Korea's Red Cross which is organising the video reunions, said time was running out for many separated families as old age took its toll.

"The pain and suffering from the separation is enormous," Han told his North Korean counterpart, Jang Jae-on, over the link.

"We need to work with the spirit of 'in spite of everything', overcome politics, economic and military problems and solve this issue."

The South Korean sisters were glad of even just two hours with their brother.

"I hope that other families, like us, can see each other like this, laugh and, even though we can't meet, be content that we are living under the same sky," said one of Jong's sisters, Suh-young. (Additional reporting by Reuters TV and Jessica Kim) (Editing by Jonathan Thatcher; jack.kim@reuters.com; Reuters Messaging: Jack.Kim.reuters.com@reuters.net; +822 3704 5645))

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