PRIME Minister Hun Sen has cancelled a trip to the coastal province of Kampot, citing fears of a tropical storm that is set to sweep through southern Cambodia this week.

Hun Sen was scheduled to attend the groundbreaking ceremony of the Kamchay hydropower dam in Kampot today but expressed concerns about safety in the wake of the helicopter crash that killed National Police Commissioner Hok Lundy and three others on November 9.

It is believed the helicopter crashed due to heavy rain.

"I will not take any risk because of the accident that happened to our four patriots flying at night and in heavy rain," Hun Sen said at the opening of an ethanol factory in Kandal province Monday. "We regret their loss."

Meanwhile, Lim Kean Hor, minister of Water Management and Meteorology, has issued a public notice warning that heavy  rain and electrical storms are expected to pound the  southern coast in the next few days and that locals should exercise caution.

"All travellers by land, sea and air have to increase their attention in order to avoid any accidents that might occur," the statement said.

The Vietnamese government has issued similar alerts over tropical storm Noul, which is expected to make landfall off the Vietnamese coast late Monday.

The warnings come after a fortnight of unusually heavy downpours in Vietnam, which has seen record floods across the country.

ADDITIONAL REPORTING BY AFP