BANGKOK (Reuters) - Businesses in Thailand’s southwestern Petchaburi province blocked doors with sandbags and bricks against possible flooding on Tuesday as heavy rains threatened to cause a dam to overflow.

Rain storms are forecast through coming days, and the head of Thailand’s military government warned that evacuation plans might need to be set in place.

“Many areas might need to have an evacuation plan in place,” Prime Minister Prayuth Chan-ocha told reporters as he prepared to visit the province, some 168 km (104 miles) southwest of Bangkok, on Wednesday.

“Any homes downstream must be prepared to evacuate to higher ground,” he added.

Thailand suffered its worst floods in half a century in 2011. The floods killed more than 900 people, crippled industry and dented economic growth.

Officials in Petchaburi said they were confident that water levels at the Kaeng Krachan Dam and any water run-off could be managed.

“Four districts could be affected ... The governor and local administration are preparing sandbags and water pumps,” Interior Minister Anupong Paochinda told reporters in Bangkok on Tuesday.

Television news channels showed residents in Petchaburi laying sandbags and bricks in front of the doorways to shops and banks, and authorities intended to issue warnings to tourists visiting resorts on the Gulf of Thailand’s coast.

“Operators and resort owners are aware of the situation. We will send an alert to tourists,” Tourism Minister Weerasak Kowsurat told reporters.

The current rainy season has already caused havoc in neighboring Cambodia and Laos.

In Laos, 31 people have been confirmed dead and 130 are still missing after a part of hydroelectric project in the southern province of Attapeu collapsed last month.

The company building the dam has said heavy rain and flooding caused the collapse.

Cambodia’s National Disaster Management Center said flooding caused by rising water levels in the Mekong River has killed eight people and 5,000 families have been evacuated from across five provinces.