SEOUL - Top-level military officials from South Korea and the Democratic People's Republic of Korea (DPRK) continued on Monday their second round of emergency contact for more than 19 hours at the border village of Panmunjom amid tense situation with both militaries put on highest alert.

South Korean President Park Geun-hye's chief security advisor Kim Kwan-jin and top DPRK leader Kim Jong Un's chief military aide Hwang Pyong So started the second round of closed-door meeting from 3:30 pm (0630 GMT) Sunday which continued as of 11 a.m. Monday.

South Korean Unification Minister Hong Yong-pyo and DPRK's United Front Department director Kim Yang Gon in charge of inter- Korean relations each accompanied them to the second meeting after the first dialogue, which ran for nearly 10 hours until the early hours of Sunday.

The first round, the highest-level talks between the two Koreas since President Park took office in February 2013, ended without final agreement amid differences over landmine blasts and propaganda broadcasts in border areas that escalated tensions recently.

The South Korean side called for clear acknowledgement and apology for the mines explosion and shelling attack on the DMZ, while the DPRK demanded the stop of propaganda broadcasts in South Korean army units along the border.

The two sides were also known to have discussed a broad range of inter-Korean issues, including the reunion of Korean families separated by the 1950-53 Korean War and the so-called May 24 economic sanctions imposed by South Korea on the DPRK caused by what Seoul claimed was Pyongyang's torpedoing of a South Korean warship.

During the talks, the DPRK denied any involvement in the Aug. 4 explosion of landmines on the southern section of the DMZ, which wounded two South Korean soldiers on patrol duty. South Korea claimed the mines had been deliberately planted by DPRK forces.

On Aug. 10, South Korea resumed broadcasting propaganda messages with loudspeakers, silenced for the past 11 years, in retaliation for the landmine blast. The DPRK called for the immediate stop of the psychological warfare during the meeting. Pyongyang has claimed the blast was a fabrication by Seoul.

South Korea said that it fired back a barrage of artillery into the DPRK in frontlines areas Thursday after the DPRK shelling of the southern part of the DMZ, but Pyongyang also denied the allegation during the first round of talks.

Despite the wide gaps to be bridged, the resumption of the top- level talks and the ongoing marathon dialogue indicated a strong willingness from both sides to defuse tensions soaring to the highest level with both militaries on maximum alert.

Nearly 70 percent of DPRK submarines left their bases, with the second round being under way, the South Korean military said Sunday. It was 10 times the rate under normal situations, raising anxieties on the South Korean side as the military was unable to track DPRK submarines with its surveillance devices.

The DPRK also doubled artillery forces in border areas, enabling them to fire at any time. Pyongyang has placed its frontline combined forces to enter a state of war, while South Korean troops remained on the highest alert.

South Korean and the United States raised their joint reconnaissance level toward the DPRK to the second highest Saturday, scrambling four fighter jets each to the South Korean sky on the same day.