Cambodia's Prime Minister Hun Manet on Saturday said 20 soldiers were killed in an ammunition blast at a military base in Kampong Speu province, west of the capital Phnom Penh.

"I am deeply shocked to receive the news of the ammunition explosion incident," Hun Manet said in a statement on Facebook and expressed his "deepest condolences" to the families of those killed.

Cambodia's military said a "warehouse ammunition explosion" had destroyed a truck fully loaded with weaponry. Four buildings have been destroyed.

The exact cause of the blast remains unclear.

Pictures circulating on social media showed damaged buildings, including houses with holes in their roofs, and smoke still rising.

Hun Manet said he had ordered defense chiefs to urgently arrange funerals for the soldiers who died.

He also said that the families of those killed would receive roughly $20,000 each (€18,687), while injured soldiers would get $5,000.

kb/dj (AP/AFP)