A ferry boat capsized in Burma's Ayeyarwaddy delta on Friday, killing at least 20 people and leaving more than a dozen missing, police have said.

Thirty people were rescued after the vessel capsized in the Ngawun river at around 7:30pm Friday night, police officer Nay Lin Tun said.

As many as 66 people had been on the ferry, which started to sink after colliding with a boat carrying gravel.

Most of the ferry’s passengers are believed to have been returning from a wedding ceremony.

The ferry was travelling from Pathein to Yakhinekone village.

Boat accidents are common in Burma, where most people rely on using crowded boats to travel and transport goods.

Survivors of the ferry sinking recover from the incident in Pathein, Myanmar (AP)

Government oversight is lax and poor maintenance and overcrowding also make vessels more prone to capsizing.

In October, 48 people died after an overcrowded ferry capsized on the Chindwin river in central Burma.