By Ju-min Park
SEOUL (Reuters) - South Korea proposed on Monday to resume stalled talks with North Korea, an overture that comes amid heightened diplomatic tension after Seoul's key ally the United States blamed the North for a cyberattack on Sony Pictures Entertainment.
North Korea has denied responsibility for the hack against the U.S.-based film studio arm of Japan's Sony Corp, which distributed a comedy film featuring an assassination plot against the North's leader, Kim Jong Un.
Pyongyang subsequently blamed Washington for its own internet outages, and has denied any involvement in recent system breaches into South Korea's state nuclear power operator.
Seoul's unification minister said the South had sent a letter to Pyongyang seeking negotiations, which it hopes to hold in January and would cover issues including reunions for families separated by the 1950-1953 Korean war and possible co-operation projects.
The North had accepted the letter but had yet to respond, South Korean Unification Minister Ryoo Kihl-jae told a news briefing.
"I don't think we will have any particular agenda, but our position is to discuss everything that South and North have mutual interests in," said Ryoo, noting that 2015 marks the 70th anniversary of Korea's independence from Japan.
A delegation of high-level North Korean officials made a surprise visit in October to the closing ceremony of the Asian Games hosted by the South, and promised to reopen dialogue between the two. However, the two sides failed to hold follow-up talks as tension persisted, with the North lashing out at the South over anti-Pyongyang propaganda leaflets sent to the North via balloon by activist groups.
Military officials from North and South Korea met in October to discuss border altercations, including exchanges of fire, but they did not resolve their differences.
South Korea imposed a broad set of sanctions on Pyongyang in 2010 following the sinking of a South Korean corvette that killed 46 sailors. South Korea blamed the North, while Pyongyang denied it was responsible, and the issue has been an obstacle to re-engagement ever since.
Ryoo said South Korea would explain to the North its inter-Korean cooperation plans, including a peace park at the demilitarized zone, adding that it was seeking a fresh round of reunions for families separated by the Korean War before the Lunar New Year holidays in February.
The two Koreas have remained technically at war for more than six decades as the Korean War ended in an armistice, not a peace treaty. Reunification of the Korean peninsula has been a priority for South Korean President Park Geun-hye.
(Editing by Tony Munroe and Alex Richardson)