SEOUL, South Korea — South Korea is confident that there is no basis to the recent swirl of rumors that the North’s leader, Kim Jong-un, ​is gravely ill, ​the South’s chief policymaker on the North​ said in comments reported on Monday.

“Our government has enough information-gathering capabilities to say confidently that there is nothing unusual” about Mr. Kim’s health, Kim Yeon-chul, South Korea’s unification minister, said during a forum on Sunday. Video footage of his comments was ​made available on Monday.

The comments were South Korea’s most categorical rebuttal yet of the recent reports about the North Korean leader, some of which said that he was “in grave danger” or had become “brain-dead” or was in a “vegetative state” after botched heart-valve surgery​.

​It is highly unusual for a senior South Korean official to publicly dispute news reports about what is happening inside North Korea’s secretive leadership. Normally, South Korean officials maintain a neither-confirm-nor-deny policy, at least on the record, for fear of disturbing sensitive relations between the two Koreas.