A North Korean soldier was shot dead by Chinese police after crossing the border and reportedly killing four people, Beijing acknowledged amid harsh criticism over slowness in releasing information.

"After the incident occurred, the Chinese police immediately launched a manhunt operation," foreign ministry spokesman Hong Lei said in comments posted on the ministry's website after a regular press conference on Wednesday.

"During the operation, the killer was shot and died later after medical treatment failed to revive him."

South Korea's Yonhap news agency and Dong-A Ilbo newspaper reported on Monday that a young North Korean believed to be a runaway soldier killed four Chinese during a robbery after he crossed the border into northeastern China late last month in search of food.

The victims, two elderly ethnic Korean couples, were either shot dead or beaten to death, Dong-A said, adding the soldier was later shot and captured by Chinese authorities.

Ethnic Koreans make up about 30 percent of the population in China's Yanbian Korean Autonomous Prefecture, which borders the North.

North Korea's military has been no exception to the country's chronic food shortages with troops known to cross the border in search of food.

Describing the incident as an "individual criminal case", Hong added that China and North Korea were taking it "very seriously", with Beijing lodging diplomatic representations and Pyongyang expressing regret and sympathy.

"Competent authorities of the two sides are carrying out follow-up investigation and dealing with the case in accordance with the law," he said, although he avoided any direct mention of the four Chinese citizen deaths.

China's Global Times tabloid, which has close ties to the ruling Communist Party, carried a blistering criticism of the delay in releasing information.

"Obviously, it is inappropriate that no voice over the case, involving the death of four Chinese citizens, has been heard from the Chinese side for more than a week, until it was first reported by a South Korean news agency," the paper said in its English edition Thursday.

The paper lamented that Chinese people invariably get first word of "diplomatic incidents" in China from "foreign or third-party reports" rather than official channels and domestic media.

"Chinese authorities and the mainstream media have no excuse for maintaining this norm, since if it continues, both government departments and Chinese media will lose their credibility," it added.

China, which helped defend North Korea during the 1950-53 Korean War, has long been the isolated country's key ally and aid provider, and the Global Times said: "Maybe the relationship between Beijing and Pyongyang is deemed too 'sensitive'."