North Korea is set to try two US citizens for "crimes against the state", according to the country's state news agency, KCNA.
The North Korean leader Kim Jong Un has been taking a tour around a naval submarine.
Photographs show him testing equipment, dispensing advice, and meeting the crew.
They gave him a compulsorily warm welcome.
North Korean officials have joined bereaved families and residents in mourning those killed when a building collapsed in Pyongyang last week.
The country's government today offered a rare public apology over the accident, saying the construction of the apartment "was not done properly" and officials "supervised and controlled it in an irresponsible manner".
North Korean leader Kim Jong-un reportedly suffered deep anguish over a building collapse in Pyongang that left many dead, according to the country's state media.
The Korean Central News Agency said Kim "sat up all night, feeling painful after being told about the accident", South Korea's Yonhap news agency reported.
A North Korean official added that the leader "instructed leading officials of the party, state and the army to rush to the scene, putting aside all other affairs".
The number of casualties in the accident has not been revealed, although officials in Seoul believe it could be "considerable", Yonhap said.
"In North Korea, it is common that people move into a new apartment even before the construction is completed. About 92 households may have been living in the apartment," a South Korean government official said.
An apartment building under construction in the North Korean capital of Pyongyang has collapsed, causing an unknown number of casualties, according to South Korean news agency Yonhap.
The incident was marked by a rare apology from senior officials, as "the construction of an apartment house was not done properly, and officials supervised and controlled it in an irresponsible manner".
Complaints from the North Korean embassy against a hair salon's poster poking fun at their leader's unusual hairstyle has reached the corridors of power in Whitehall.
The Foreign Office has confirmed it received a letter this week complaining about the picture of Kim Jong-Un which was displayed in M&M hair Academy's window in South Ealing.
The advert said: "Bad Hair Day? 15% off all gent cuts through the month of April."
Staff at the west London salon were confronted by two men claiming to be North Korean officials over the marketing stunt earlier this month.
An advert poking fun at North Korean dictator Kim Jong-un infuriated some officials from the country's nearby London agency.Read the full story ›
Strict guidelines released in North Korea say all men should have the same haircut as leader Kim Jong-un.Read the full story ›
Kim Jong Un has received 100% of the vote in the country's parliamentary elections, according to state media.
KCNA news agency says the North Korean leader was elected to the Supreme People's Assembly unanimously by the people of his Mount Paektu constituency on Sunday.
Ballots for each district contained only one name each. The polls are seen by some outside the country as an opportunity for the state to check on any citizens who may have attempted to escape to China or South Korea.
However, the government's news outlet hailed a 100% turnout across the country "except for those on foreign tour or working in oceans".