Recent satellite photos suggests that North Korea is preparing for fresh submarine-based missile tests, an expert has said, amid heightened tension between the US and North Korea over the communist state's successful launch of an inter-continental ballistic missile.

Referring to photographs posted on Aug. 11 on 38 North, a US website specializing in North Korea analysis, Joseph Bermudez, a North Korea specialist, claimed that they could indicate preparations for a new test of a submarine-launched ballistic missile.

"Recent commercial satellite imagery reveals several developments suggesting that North Korea may be accelerating the development of the sea-based leg of its nuclear forces," he said.

North Korea carried out its first successful test-launch of an ICBM on July 4, followed by another successful launch of an ICBM on July 28. The tests have raised concerns that the North has the ability to put the entire US within its range of attack.

On Aug. 5, the United Nations Security Council voted unanimously for fresh sanctions on North Korea, after it launched two ICBM tests last month, which has prodded Pyongyang to threaten a missile strike around the US territory of Guam. (Yonhap)