Relatives visit sub collision site

The attack sub was bursting onto the surface at a 45-degree angle

Tearful relatives of the nine Japanese missing from the trawler that sunk after being rammed by an American submarine have visited the accident site off Hawaii, where they called out their loved ones' names and cast flowers into the sea.

Please join me in a moment of silence for those missing, their families and our friends, the people of Japan

George W Bush

The US Navy, while continuing its search for the missing, was preparing to send sending underwater robots to survey the seabed where the ship sank.

The accident comes five months after a top officer in the US Navy raised concerns about accidents at sea.

Nine students who survived the accident returned to Japan

And it comes at a tense time for US-Japan relations, already under strain over incidents involving US troops on the Japanese island of Okinawa.

Nine students who were among the 26 people rescued from the stricken Ehime Maru arrived back in Japan on Tuesday.

The nuclear-powered submarine, USS Greenville, was practising an "emergency blow," bobbing rapidly to the surface, when it hit the fishing vessel on Friday.

Scanners to seabed

On Tuesday, Japan reiterated its call for the US to salvage the sunken ship, heeding relatives pleas' for confirmation as to whether it was a tomb for their loved ones.

The Scorpio can transmit video images from the seabed

No decision about a salvage operation has yet been made yet, according to US officials. But a survey of the area, which would help determine the feasibility of salvage work, has been planned.

The remotely-operated vehicle Scorpio II was flown to Hawaii on Monday night from California, the US Navy said.

It is equipped with a sonar scanning system and can transmit video images from the ocean floor.

Also dispatched was the Klein 2000 Side Scan Sonar System, while the remotely-operated "Deep Drone" was on its way.

Safety concerns

As the hope of survivors dimmed, US officials have focused on how the accident occurred.

Concerns about lapses in seamanship and navigation were raised last year by navy officials.

Four of those missing from the Ehime Maru, which was on a studies voyage, are 17-year-olds

In September, a top naval officer called for a one-day "safety standdown" requiring all vessels to review navigation procedures.

The Navy said then that there had been six major ship collisions over the previous 12 months.

On Monday, US President George W Bush made his first public comments on the tragedy.

"I would ask for your prayers for those still missing after the tragic accident," the president told US troops during a visit to Fort Stewart military base, Georgia.

He called for a moment of silence for the missing.

Friday's accident comes as Japanese resentment to the US military has intensified, following a row over an offensive e-mail by the chief of US military in Okinawa, who called his hosts "nuts" and "wimps".