WASHINGTON (AP) _ President Reagan's chief spokesman made light of reports Tuesday that President Kim Il Sung of North Korea apparently had not been killed in a shooting incident and was shown alive on television with the leader of Mongolia.

''Kim Il Sung rose from the dead ...,'' White House deputy press secretary Larry Speakes said. ''I don't blame him. I'd come out if the president of Mongolia was in my front yard, too.''

He volunteered his comment at a news briefing. No one had asked about Kim.

Pyongyang's official Korean Central News Agency said Kim had gone to Pyongyang Airport to welcome Mongolian President Jambyn Batmunkh. Japanese television stations showed rare segments from North Korean television of Kim, in a dark overcoat and cap, walking up a gold-bordered red carpet to meet Batmunkh, shaking hands and embracing him.

Questions about Kim were raised Monday when the South Korean Defense Ministry in Seoul said North Korean propaganda loudspeakers along the demilitarized zone between North and South Korea announced that Kim was killed in a shooting incident.