Seoul, Jan 07 (Agencies): South Korean and US forces have downgraded their defensive alert against the North based on intelligence that Pyongyang has relaxed the standby status of military units on the west coast, a news report said on Friday.

The North Korean units, including artillery bases likely to have been involved in the shelling of a South Korean island on November 23, had been on special standby but now appear to be on routine operations, South Korea's Yonhap news agency said.

"We're looking at whether these steps are linked to the conciliatory gestures coming from the North with its offer for talks," Yonhap quoted the Government source as saying.

South Korea's defense ministry and an official at the Combined Forces Command declined to confirm the report. "We do not discuss intelligence matters," the official said.

South Korea's Chief of Naval Operation Kim Sung-chan told local reporters on Friday it and the US military will double the scale of combined anti-submarine drills this year, including those in waters near the disputed sea border with the North, Yonhap reported.