Hacking attempts on the South Korean military's computer networks have markedly increased this month amid strained ties with China and North Korea's continued belligerence, the defense authorities said Tuesday.

"Recently, attempts to breach (our) cyber networks have somewhat increased," Moon Sang-gyun, a spokesman for the Ministry of National Defense, said at a press briefing.

But there has been no actual damage, he added.

He did not elaborate on the source of the cyberthreats he mentioned.

Another military official said later that a total of 44 hacking attempts were detected on the networks of the defense ministry, the Defense Acquisition Program Administration, the Agency for Defense Development and other key military facilities between March 9 and 15.

It represents a sharp rise from 25 recorded a week earlier.

There was only one case found between Feb. 16 and 22, according to the official.

The trend added to concern about hostility among Chinese officials and some ordinary people to South Korea over its decision to let the US military position a cutting-edge US missile defense system here, widely known as THAAD.

Last month, Seoul's defense ministry announced a land-swap deal with the local retail giant Lotte Group for a site for the THAAD battery. Lotte has also become one of the main targets of China's retaliation, as it's staunchly opposed to the allies' move to beef up their capability to intercept North Korea's missiles.

Military officials, however, dismissed concern about the possible vulnerability of the military's intranet, saying it's completely "separated" from the Internet server.

They pointed out the government has already elevated the cyber terror alert level by one notch. The military also raised the stage of "INFOCON," which is an information-related defense alert system.

The military's intranet suffered the first known hacking attack in September last year for which the North was believed to be responsible. (Yonhap)