Brazil's state oil giant Petrobras said on Tuesday it would extend the investigation of last month's sinking of its biggest offshore oil rig beyond this Friday's deadline.
Petrobras reportedly said that the investigation commission and representatives of Norway's shipping classification agency Det Norske Veritas, which is acting as an independent consultant in the probe, had asked for more time.
Company officials cited "complexity of works" as the main reason for the delay. The platform, known as P-36 and which Petrobras said was the world's biggest deepwater rig
, is lying on the sea floor at a depth of 4,500 ft. (1,360 m).
Three powerful blasts rocked the rig last month, killing 11 crew and making it lose stability and sink five days afterwards off the coast of Rio de Janeiro state, despite risky and expensive salvage attempts
Some experts have said it would be all but impossible to detect what had caused the blasts.
On April 20, which was the initial deadline, the commission will present its preliminary report with some thoughts on the reasons of the tragedy outlined and also with an estimate of how much time the commission would need to finish the probe.
Petrobras officials have said that in two to two-and-a-half years the company would receive a new rig
to substitute the sunken $360 million one. The rig accounted for about 6 percent of Petrobras', and Brazil's, crude output.