White columns of vapour rise from the Pacific Ocean off Iwo Jima in Japan. (Reuters)

Tokyo, July 3 (Agencies): A mysterious column of water vapour shot a kilometre into the sky near a remote Pacific island off southern Japan.

The column of steam close to Iwo Jima, about 1,120 km southeast of Tokyo, was likely to have been caused by an underwater volcanic eruption, and ships should avoid the area, Japanese officials said.

A coast guard crew flew over the area to try to determine what happened. Japan’s meteorological agency said there was no danger of tsunami, sometimes caused by undersea seismic activity.

Japanese troops stationed on Iwo Jima yesterday reported seeing the massive, cloudy column rise from the sea, about 50 km southeast of the small island, said Maritime Self-defence Forces spokesperson Hiroshi Shirai.

“It’s highly likely that it’s caused by an eruption of an underwater volcano,” coast guard spokesperson Shigeyuki Sato said of the strange occurrence. “A similar eruption occurred in the area before.”

Officials who flew over the site in a helicopter said the ocean surface appeared red in the area where the column was reported, which could indicate underwater volcanic activity, Shirai said.

Coast guard aircraft crews returned with video images of the vapour plume and surrounding water, Sato said. The survey crew also found gray mud rising from the bottom. It was not immediately known if volcanic gases were being released.