DHAKA (AFP) - Bangladesh's coastguard on Wednesday found five dead and nearly 200 injured on a stricken people-smuggling boat it rescued in the Bay of Bengal after clashes between the would-be migrants and crew, officials said.

More than 300 people including two Thai crew and an alleged people trafficker from Myanmar were on board the Malaysia-bound vessel, which was found seven nautical miles southeast of Bangladesh's southern-most Saint Martin's Island in rough seas, they said.

Thousands of poor Bangladeshi and ethnic Rohingya refugees from Myanmar try to migrate to Malaysia every year on a perilous and sometimes fatal 3,200km journey.

"We searched the ship and found five bodies of Bangladeshi nationals. All of them were shot dead by the crew and the traffickers," coastguard commander Harun-or-Rashid said by phone from the island close to the Myanmar border.

Passengers said clashes erupted after they had been kept on the ship for more than two weeks with little or no food as the traffickers waited to pick up more migrants instead of setting off for Malaysia straight away, he said.

Once the fighting began, traffickers from other nearby boats began to fire on the ship, Rashid added.

"We found 318 people on the ship, which is a big Thai cargo boat.

"At least 23 of the passengers had bullet wounds and were being sent to a hospital. Their condition is not critical," he said.

"Another 151 were also injured or were starved for up to 20 days. Some of them were stabbed by knives during the clash," he said, adding that the ship's engine had broken down after the fighting.

Two Thai crew and a Myanmar trafficker were arrested, he added.

One of the passengers said from aboard the ship that they were fired on as they tried to leave Bangladesh's southern coast, near neighbouring Myanmar.

"They then fired at us from another ship and five to six people have died. The bodies are in the lower deck," passenger Ziaur Rahman said.

Mr Rahman, from Bangladesh's southernmost town of Teknaf, said he paid a human trafficker about US$2,000 for the boat journey to Malaysia and that others paid more.

Coast guard commander Rashid said the traffickers collected would-be migrants from all over the country and used small boats to ferry them to a big ship near Saint Martin's Island.

"Once the ship is filled up, it then starts the journey for Malaysia," he said, adding the coastguard had seized several several such boats in recent months.

Bangladesh's coastguard and border forces have launched crackdowns on economic migrants, confiscating their ships and arresting a number of human traffickers.