Updated 14:05

The number of people killed when a ferry capsized on Tanzania's Lake Victoria has now reached more than 170.

The MV Nyerere ferry capsized just metres from the dock on the island of Ukerewe on Thursday afternoon.

It's believed the vessel was overcrowded with more than 300 people on board.

Amid the continuing rescue effort, officials said a man has been pulled alive from the capsized vessel after two days.

It's believed the man - who's thought to be an engineer - had shut himself in a "special room" sealed with enough air to allow him to stay alive.

Photo taken on Sept. 21 shows the scene of the rescue effort in Tanzania. Picture by: Xinhua/Xinhua News Agency/PA Images

Meanwhile, it's still not known exactly how many people were on board the boat when the disaster happened, amid reports it was only meant for around 100 people.

The captain is being questioned, while Tanzania's president John Magufuli has also ordered the arrests of those responsible for operating the ferry.

Four days of national mourning have also been declared in the country following the disaster.

Lake Victoria - Africa's largest lake - is spread across Tanzania, Kenya and Uganda.

The have been several major ferry disasters on the lake over the years, with more than 800 people killed when the MV Bukoba sank in 1996.

Additional reporting by IRN