Twelve seafarers are missing after their general cargoship sank off China.

Radio New Zealand said the 6,000-dwt Kiribati-flagged Xiang Zhou (built 2009) went down in the Yangtze River estuary off Nantong.

A collision was blamed for the incident, according to Shanghai rescue authorities.

Two crew were rescued by nearby ships.

A search operation has been launched.

The vessel, operated by Ningbo Shanlun Ship Management, was en route from South Korea.