South Korea says North Korea has fired a barrage of shells into waters near a disputed sea border in the Yellow Sea amid high cross-border tensions.
Officials in Seoul say North Korea's battery opened fire in waters off the west coast on Monday, AFP reports.
Yonhap news agency said the North fired about 100 rounds.
The North's move came shortly after South Korea ended a five-day naval exercise in the Yellow Sea.
In July, the United States and South Korea carried out a series of naval exercises off the Korean peninsula despite threats from North Korea that it might retaliate.
The US and South Korea said they aimed to send what they are calling a clear signal to the North, after the sinking of a South Korean warship in March.
North Korea denies any involvement in the incident.