SINGAPORE - Foreign Minister Vivian Balakrishnan has written to his Cambodian counterpart to express his condolences over the collapse of a building under construction that killed 28 people last weekend.

Writing to Cambodia's Deputy Prime Minister and Minister for Foreign Affairs and International Cooperation Prak Sokhonn in the letter dated Wednesday (June 26), Dr Balakrishnan offered his "deepest sympathies on the loss of lives and injuries" as a result of the building collapse in the town of Sihanoukville last Saturday.

Some 26 people were injured after the structure collapsed without warning before dawn.

Dr Balakrishnan also offered Singapore's assistance to help Cambodia in the aftermath, noting that Prime Minister Lee Hsien Loong had extended the offer to Prime Minister Hun Sen when they met in Bangkok on the sidelines of the 34th Asean Summit last Sunday.

"Our thoughts and prayers are with those who lost their loved ones and we wish the injured a speedy recovery," he wrote, the Ministry of Foreign Affairs said in a statement on Thursday.

The collapse of the seven-storey steel and concrete structure was one of Cambodia's recent deadliest accidents. Construction workers who were asleep at the site were among those trapped under rubble following the collapse.

Rescue workers pulled the last two survivors from the wreckage on Monday.

A Cambodian court on Tuesday charged seven people - including the Chinese building owner and construction supervisor - with involuntary manslaughter and conspiracy over the collapse.

An investigation into the accident is underway.