About 100 South Koreans have crossed the border to the North to meet relatives they have been separated from since the Korean peninsula was divided after the 1950-1953 war.
A six-day reunion started on Saturday in the Mount Kumgang resort in the North.
Most of the participants were in their 70s or older, eager to meet their family members before they die.
Millions of Koreans were separated during the war which ended in an armistice instead of a peace treaty.
There are no mail, telephone or e-mail exchanges between ordinary citizens from the two Koreas. Nor can they travel to the other side of the peninsula without government approval.
Family reunions began in 2000 following a landmark inter-Korean summit, but have been on hold since 2007 following political tensions.
About 16,000 people from the South and the North have been able to meet since the reunions began. Nearly 4,000 others have seen relatives in video reunions.
North Korea agreed last month to resume the reunions in a move seen as conciliatory gesture after months of tensions with South Korea and the United States over the North's nuclear and missile developments.
Al Jazeera's Steve Chao, reporting from Sokcho in South Korea, said: "These family reunions are very much seen as a sign of warming relations.
|Millions of people were separated by the
Korea war [Reuters]
"The South has pushed for more reunions, mostly because of concerns that many of these family members are dying.
"So far, the North has balked at the idea but organisations like the Red Cross and business people are trying to convince the North not to politicise the event."
Donald Kirk, a Korea specialist and writer for the Christian Science Monitor, told Al Jazeera that given the controversy surrounding the North's nuclear programme, further reunions may not be possible.
"South Korea's president has been talking very tough for the last two or three days. He is saying that North Korea has to agree to a package deal to give up all its nuclear weapons," he said.
Kirk said: "I don't think that North Korea is going to be very happy about that, and [this] could complicate any moves towards further reunions.
"I am not saying there won't be more family reunions ... but this reunion is the first in two years and it's very up in their air whether or not there will be another one any time soon as long as South Korea is adopting what is regarded in some quarters as a hardline attitude."
International pressure is growing on Pyongyang to abandon its nuclear weapons programmes and return to stalled disarmament talks.
North Korea boycotted the six-nation nuclear talks in April, but Kim Jong-il, the president, has reportedly expressed interest in "bilateral and multilateral talks," indicating the North could rejoin the nuclear negotiations involving the US, China, Japan, South Korea and Russia.
Lee Myung-bak, the South Korean president, said at the end of the G20 summit in Pittsburgh on Friday that North Korea must return to talks "with sincerity."
"If they are sincere, then we are ready to provide them with whatever is necessary," Lee said.
Source: Al Jazeera and agencies