Bangkok, Thai authorities have issued a warning to people residing in the country's southern provinces to brace for flash floods over the weekend, after tropical depression "Etau" will make landfall.

The depression will strengthen the northeasterly wind, leading to heavy to very heavy rain in southern provinces of the country, causing flash floods in some areas, Xinhua news agency quoted the Office of National Water Resources as saying on Friday.

At Samila Beach in Songkhla province, officials raised yellow flags, to warn tourists that swimming in the sea could put them at risk.

The Office of the Prime Minister had earlier informed provincial administrations to keep people informed of the latest situation and to prepare for evacuations.

Meanwhile, the Meteorological Department on Friday also warned the effects of tropical storm "Vamco", which is forecast to make landfall in central Vietnam on Sunday, will also affect Thailand with heavy rain.

Packing winds of up to 100 kph at its centre, the storm is heading toward Vietnam at a speed of 20 kph and is steadily gaining in strength, the Department added.