The Paris airport collapse that killed four people in May was probably caused by metal struts piercing the building's concrete vaulted roof, an official report said yesterday.

　　The Transport Ministry said preliminary findings suggested that the "dominant cause" of the partial collapse of terminal 2E was "linked to the perforation of the vault by the struts."

　　But the report said experts had yet to determine why the struts broke through the concrete and why the accident happened when it did. The metal struts were a key part of the structure, holding apart the arched concrete roof and the glass that enveloped it.

　　The report also blamed the poor quality of the concrete for the May 23 disaster, in which falling glass, steel and masonry killed four travelers - two Chinese, one Czech and one Lebanese. Three others were injured.

　　"It's probable this perforation was made possible by the prior gradual deterioration of the concrete," the statement said.

　　The ministry, citing the findings, brushed aside speculation the accident was caused by ground movement or the problems that appeared in construction.

　　Pylons holding up the section of the three-building terminal that collapsed had to be reinforced after cracks appeared - among the problems that delayed the terminal's opening.

　　(The Associated Press)