An inter-Korean wireless communication network for naval vessels has virtually stopped functioning as North Korea has failed to respond to South Korean calls.

The two Koreas established the communication network in June 2004 to prevent accidental clashes between South and North Korean naval vessels.

According to the Ministry of National Defense's report to the National Assembly, South Korea placed 104 calls as of October last year but North Korea responded just once.

Due to the near absence of reply, it would be difficult to engage in immediate communication if an accident occurred between the two Koreas' naval ships on waters off the west coast.

The ministry also said that inter-Korean exchange of information about illegal fishing by Chinese fishermen on the Northern Limit Line had been suspended since last May.

In addition, the ministry reported that three military communication lines on the east coast are in operation but in poor quality.