TOKYO — South Korea's spy agency told lawmakers Wednesday it does not believe that North Korean leader Kim Jong Un had heart surgery last month and has determined that his three-week absence from public view was probably linked to fears over the coronavirus pandemic.

Officials of the National Intelligence Service told a parliamentary committee that the reports of heart surgery, first carried by South Korean website Daily NK and then amplified by Western media into talk that Kim was gravely ill or even dead, were “groundless,” according to a lawmaker on the intelligence committee.

“He was normally performing his duties when he was out of the public eye,” said Kim Byung-kee of the ruling Democratic Party, describing the intelligence reports in a briefing with reporters.

Speculation about Kim’s health swirled after he failed to attend a ceremony to mark his grandfather’s birthday on April 15 and did not appear in public for the rest of the month.

Rumors of his death were dispelled when Kim reappeared on state media on Saturday, with extensive footage of him opening a fertilizer factory the previous day before a cheering crowd, all wearing face masks.

Officials in the United States and South Korea, speaking on the condition of anonymity to discuss sensitive intelligence, have said Kim retreated to a beach resort in Wonsan on the country’s east coast after learning in mid-April that subordinates in his vicinity had suffered from a fever.

The hiatus was not Kim’s first absence from the public eye this year. He laid low for three weeks between late January and February and was not seen on state media for another 13 days between the middle and end of February.

Kim Byung-kee said the North Korean leader has made only 17 public appearances this year, compared with an average of 50 over the same period in previous years, which the NIS linked to a possible coronavirus outbreak in North Korea.

Although North Korea’s government insists it has no confirmed cases of the novel coronavirus, it has repeatedly emphasized the threat to the country from the disease it causes, covid-19.

The NIS said the virus could have entered the country from China before the border between the two countries was closed in late January.

“It cannot be ruled out that there has been an outbreak in North Korea,” Kim Byung-kee said. “Kim Jong Un had focused on consolidating internal affairs such as military forces and party-state meetings, and coronavirus concerns have further limited his public activity.”

The NIS said the prolonged closure of the border has added to the economic hardships of North Korean people and temporarily pushed up the price of imports such as spices and sugar, as well as the dollar’s exchange rate against the local currency.

That, in turn, caused an outbreak of panic buying among Pyongyang residents, it said, which provided more fuel for the rumor mill surrounding the health of the nuclear-armed dictator.

Since then, authorities have cracked down on hoarding and stepped up emergency food imports, allowing prices to more or less stabilize, the NIS said.

Meanwhile, there is no sign of a slowdown in North Korea’s efforts to improve its missile defense capability, with weapons tests continuing at a rapid pace this year.

The Center for Strategic and International Studies released satellite images Tuesday of a new facility near Pyongyang Sunan International Airport that it said is “almost certainly related to North Korea’s expanding ballistic missile program.”

One building within the facility is large enough to accommodate an elevated Hwasong-15 intercontinental ballistic missile “and, therefore, the entirety of North Korea’s known ballistic missile variants,” it said.

Kim reported from Seoul.