HANOI, Oct. 9 (Xinhua) -- Vietnam's relevant agencies have defined four signs of wrongdoings that led to the collapse of an approach ramp leading to Vietnam's Can Tho bridge, according to local media on Tuesday.

    The 90-meter section of the approach ramp in southern Vinh Long province, which is 30 meters above the ground, collapsed on Sept. 26, killing 53 people, leaving one missing and 80 others injured.

    The first sign of wrongdoing is about execution method, in which technical requirements for casting concrete was not fully met, said Saigon Liberation newspaper.

    The second sign of wrongdoing is that the execution's surveillance work was not done perfectly.

    The third involves in the use of scaffold systems of poor quality, and the fourth is the untimely action of relevant organizations and individuals who received warnings about the presence of cracks on one side of the approach ramp.

    Prime Minister Nguyen Tan Dung has ordered a temporary suspension of the rebuilding of the collapsed ramp to ensure working safety, and asked rescue work to continue to recover the single worker believed still trapped in the debris, said Vietnam News newspaper.

    Dung told the major contractor -- a partnership of three Japanese firms Taisei, Kajima and Nippon Steel -- that their cooperation would help the national investigation committee's work. This was to identify the cause of the accident and assess the responsibilities of those involved in its construction. He has ordered the committee to report to him within a month.

    Construction of approach ramps and the cable-braced bridge's main span over the Hau River, linking Can Tho city and Vinh Long, with total length of nearly 16 km, began in September 2004.

    The investment of 295 million U.S. dollars came from official development assistance of Japan and the Vietnamese government's reciprocal capital. It is scheduled to be complete in December 2008.