South Korea is not considering lifting its four-year-old sanctions against North Korea, Seoul's unification ministry said Monday, maintaining its stance that the North should first admit to its deadly torpedo attack against the South's warship. In the wake of the sinking of the South's Cheonan warship near the Yellow Sea border with the North on March 26, 2010, which claimed the lives of 46 South Korean sailors, the Seoul government imposed a set of sanctions against Pyongyang on May 24 that year. The so-called May 24 measures, which effectively halted all inter-Korean cooperation except for the Kaesong Industrial Complex, are still in effect. "The May 24 sanctions should be maintained until North Korea takes responsible measures that can be understood by our people," said unification ministry representative Kim Eui-do at a regular briefing. "I'd like to make it clear once again that the government has never considered lifting the measures at a time when the North has not shown any changes in its attitude."    South Korea has urged the North to admit to and apologize for its attack on the Cheonan, while the North has denied any involvement in the incident. Some have expected that the Seoul government will at least ease the restrictions on its communist neighbor, taking a cue from President Park Geun-hye's initiative in Dresden. In her speech at the Dresden University of Technology last month, Park unveiled a package of proposals calling for bolstering exchanges with the North, including Seoul's humanitarian aid projects for the impoverished North. The inter-Korean relations, which had shown signs of thawing, have taken a turn for the worse in recent weeks, after Pyongyang carried out a series of provocative actions: threatening to carry out a "new form" of nuclear tests, launching mid-range missiles and conducting a live-fire exercise.