A second group of South Koreans met North Korean relatives Sunday at a reunion for families divided for decades, a day before South Korean-US military exercises that threaten to sour relations.

The reunion -- held at the North's Mount Kumgang resort from last Thursday till this Tuesday -- is the first in more than three years for families torn apart by the 1950-53 Korean War.

In the second and last round of the event, 357 southerners met 88 North Korean relatives Sunday afternoon.

The first batch of about 80 southerners returned home Saturday after a tearful reunion with their 174 northern relatives from Thursday.

Ryoo Jung-Hee, 69, called it a "miracle" that her 81-year-old brother -- dragged to the army at the age of 17 and long believed dead -- was alive in the North and looking for her.

"We even had his death certificate issued a long time ago... it was like a miracle when we heard he was alive and was looking for us," Ryoo said before departing Seoul on Sunday.

"I still can't believe this is real," she said.

Bang Rye-Sun, 89, also believed for decades that her brother five years her junior had died during the war -- until she got a call that Sang-Mok was looking for his big sister.

"I really want to tell him, 'Thank you so much for staying alive'," she said before departing for the North.

- Growing tension -

The much-anticipated event went ahead despite growing tension about the joint military drill, which has come in for fierce criticism from Pyongyang.

South Korea and the United States, which bases about 28,000 troops in the South, will Monday begin their annual Key Resolve and Foal Eagle exercises.

The allies describe the drills as defensive in nature but the North habitually condemns them as a rehearsal for invasion. It threatened earlier this month to cancel the reunion if Seoul pushed ahead with them.

The North however later agreed to go ahead with the event, in what was seen as a concession aimed at improving ties.

Relations were icy last year when the North issued a series of threats against Seoul and cancelled a planned family reunion in September, citing the South's "hostility".

The North's ruling party newspaper Rodong Sinmun on Saturday continued to heap criticism on the drills, accusing Washington of trying to hamper the improvement in cross-border ties.

"The US is welcoming the family reunion only with words... but its Secretary of State, during a recent visit to the South, emphasised that the joint drills should go ahead as planned," it said in an editorial.

"It is a vicious attempt to hobble the latest breakthrough we arranged in order to improve inter-Korean relations."

On Sunday it published an interview with three North Korean participants in the reunion, who were quoted as slamming the "US imperialist enemy" for causing the separation of families and for pushing ahead with the military drills.

"Who separated our peaceful family? It's the US!" it quoted Yang Sang-Hwan, who said he was reunited with his cousin and brother, as saying.

Even during the reunion, some North Korean relatives delivered political addresses in keeping with Pyongyang's official line, as the North's officials watched.

They typically heaped abuse on US troops stationed in the South and their regular joint drills with Seoul, according to South Korean families quoted in pool reports.

Millions of people were separated from their spouses, parents, children and siblings during the chaos and devastation of the conflict six decades ago.

The two Koreas remain technically at war after the conflict ended with an armistice rather than a peace treaty, with cross-border mail, phone calls and other civilian communications banned.

Most of the separated families have died without seeing or hearing from their loved ones again. Only 71,000 in the South -- mostly aged over 80 -- are still alive and wait-listed for the highly competitive reunion spots.

Only about 100 people on each side are chosen for each reunion based on a lottery.

Some of those who won the latest lottery gave up their spot due to failing health. Two people -- aged 91 and 83 -- travelled to the North by ambulance.

Six aged participants from the South had to cut the reunion short and were taken to hospital due to medical conditions worsened by the journey and the emotional shock.