The wastewater reportedly has caused pollution and a foul smell at the beach, prompting many complaints filed with the provincial administration.

The governor on Thursday instructed the provincial natural resources and environment office to cooperate with the municipality to investigate and take action against owners of resorts and hotels.

A survey found that more than 50 per cent of resorts and hotels with more than 60 rooms still do not have proper wastewater treatment systems.

Noppadol Ingkhawatcharakul, an official with the Phang Nga environment office, said his office would take legal action against resort and hotel owners.

Noppadol said the survey also found that households and small resorts contributed to water pollution.

As a result, the office advised the municipality to build facilities to filter and add oxygen to run-off water before it drains into the sea.