N Korea's Kim expresses condolences over virus in S Korea

North Korean leader Kim Jong Un sent a personal letter to South Korean President Moon Jae-in to express his condolences over a soaring viral outbreak, Seoul officials said Thursday.

It wasn't immediately clear if Kim's letter was an attempt to improve strained ties with South Korea amid a deadlock in broader nuclear diplomacy with the U.S. Earlier this week, Kim's sister issued insults against Moon's presidential office in her first official statement.

In his letter to Moon on Wednesday, Kim conveyed a message of comfort to the South Korean people over the cornonavirus outbreak that has infected more than 6,000 people and killed 37 others in the South, senior presidential official Yoon Do-han told reporters.

North Korea has repeatedly said there have been no cases of the virus on its soil, a claim that is questioned by many outside experts. Kim said he was worried about Moon's health and expressed frustration that there wasn't much he could do to help South Korea at this moment, Yoon said.

Kim underlined his unwavering friendship and trust toward President Moon and said that he will continue to quietly send his best wishes for President Moon to overcome the outbreak, Yoon said.

Kim also expressed his candid thoughts and opinions about the current situation on the Korean Peninsula, Yoon said, without providing details.

Moon sent Kim back a letter on Thursday conveying his gratitude to him, Yoon said.

Moon and Kim built personal ties in 2018 when they met three times and reached a series of agreements aimed at boosting exchanges and lowering military animosity.

Moon, a liberal who espouses a negotiated settlement of the North Korean nuclear crisis, also facilitated Kim's first summit with US President Donald Trump in Singapore in 2018.

But relations between the Koreas suffered a setback after a second summit between Kim and Trump in Vietnam in early 2019 ended without any deal on North Korea's nuclear program.

Some experts say North Korea is likely to reach out again to South Korea to receive help in reviving its troubled economy, since the US has said it won't ease sanctions on the North unless it takes significant steps toward denuclearization.