HONG KONG (AFP) - More than 50 people were injured when a Hong Kong ferry crashed into a seawall off the coast of the gambling enclave of Macau on Friday, officials said, the latest accident to hit the cities' busy waterways.

The crash happened when the Macau-bound ferry - reported to be a jetfoil boat - was approaching the port at around 9.30am local time (0130 GMT) and hit a concrete breakwater, a spokesman for Macau's marine department said.

The authorities earlier said around 20 people were injured but later put the figure at 57.

"The vessel was carrying a total of 220 passengers and 13 crew members. Fifty-seven passengers have suffered minor injuries, including two Koreans and one Japanese," a spokesman for Shun Tak, which operates the ferry services, said in a statement.

Passenger ferries regularly cover the hour-long distance between Hong Kong and Macau.

Local broadcaster RTHK said the ferry involved was a jetfoil and the cause of accident was yet to be determined.

It is the third accident on the Hong Kong to Macau ferry route in the past eight months.

In November, a high-speed ferry travelling from Hong Kong to Macau hit an "unidentified object" near one of Hong Kong's small outlying islands, injuring 87 people.

And last month a Hong Kong-bound Macau ferry collided with a mainland Chinese vessel, leaving 33 injured.

Fears over maritime safety in Hong Kong were sparked after a fatal collision between a passenger ferry and a pleasure boat carrying around 120 people claimed 39 lives in October 2012.

The accident was the city's worst boating disaster in decades and shocked the Asian financial hub, which prides itself on its good safety record.

An inquiry into the crash found a "litany of errors" and "systematic failings" in the marine department's safety standards.

Fatal boat accidents are rare in Hong Kong despite its crowded waters, which often see high-speed hydrofoils vying for space with tourist junks, luxury yachts and a century-old public ferry system.