HANOI (REUTERS) - At least 12 labourers were killed and more than 20 wounded on Wednesday when scaffolding collapsed at a construction project in a coastal economic zone in central Vietnam, state media reported.

The workers were sub-contractors for construction of a breakwater, led by Samsung C&T Corp, a unit of South Korea's Samsung Group, at the Vung Ang economic zone in Ha Tinh province, the online newspaper Thanh Nien (Young People) said.

"At the construction site, there were thousands of workers, so the number of workers in distress is not yet accurately calculated. Authorities are actively removing the rubble to rescue the trapped workers," Pham Tran De, deputy head of the zone's management board told online newspaper VnExpress.

Reuters could not immediately confirm the reports of the incident, which took place late on Wednesday.

"All police force, border guards, rescue teams... are mobilised to take part in the rescue," De told VnExpress.

The incident was the latest setback for the Vung Ang economic zone, which was hit by rioting and arson attacks on facilities employing Chinese workers last year, as anti-China sentiment erupted in the wake of a maritime territorial row.