China is seriously concerned about a recent collision between a nuclear submarine belonging to the United States Navy and an "unknown object" in the South China Sea, a military spokesman said on Tuesday while urging the US to offer details about the incident.

Senior Colonel Tan Kefei, a spokesperson for the Defense Ministry, said it is the responsibility and obligation of the US to give a detailed explanation of what the US Navy called a collision on Oct 2.

"We have noticed that the US military deliberately delayed (making public the incident) and concealed its details. It released a vague, brief statement five days after the collision. Such an irresponsible, nontransparent move is highly prone to creating misunderstanding and misjudgment, forcing China and other countries along the South China Sea to suspect the 'truth' given by the US and its real intentions," the officer said.

The root of the incident and its hazards lay in the fact that the US military keeps flexing its muscles and making trouble by sending aircraft carriers, strategic bombers, and nuclear submarines to the South China Sea, and that it continues to threaten countries and exacerbate tensions in the region, Tan added.

He noted the US' acts definitely endangered navigational safety in the sea, incurred concerns and worries from related nations, and also posed grim threats and risks to regional peace and stability.

And Tan stressed that the fundamental solution would be for the US to stop its provocative close reconnaissance around China's territories in the South China Sea and the military deployment targeted at China, and also to abandon its "freedom of navigation" operations.

The US Navy said on Oct 7 its nuclear-powered submarine USS Connecticut was damaged on Oct 2 when it struck an unknown object while submerged in the waters of the South China Sea. The vessel had arrived at the port in Guam. However, the US Navy gave no details about where the incident took place or the number of people who were hurt, saying only that injuries were not "life threatening".

The incident has also highlighted the severe risk of nuclear proliferation because of the submarine deal involving the US, the United Kingdom, and Australia that will likely compromise the international system for nuclear non-proliferation, induce an arms race, cause nuclear accidents, and bring grave challenges to regional peace and security, Tan added.