The lines opened between the two countries' navy and air force command headquarters, the defence ministry said. South Korea said it became the only nation to have such arrangements with China.

'The opening of hotlines will help the two nations prevent accidantal clashes,' the ministry said in a statement.

They will also help the two upgrade their 'strategic' partnership and millitary ties, it said.

The two former foes in the 1950-1953 Korean War have recently increased military cooperation amid expanding economic ties.

They aim to reduce tensions in the Yellow Sea, where Chinese vessels engage in illegal fishing, and also safeguard maritime trade there.

South Korea's air force has operated a communications hotline with Japan since 1997, and the Navy established a hotline with Russia in 2000. -- AFP