WELLINGTON: The pilot of a hot-air balloon that crashed in New Zealand killing all 11 people on board had cannabis in his system, an official report said Thursday, blaming his poor judgement for the accident.

Investigators called for tighter drug restrictions following the crash in January 2012, when the balloon hit power lines before plunging to the ground in a flaming wreck.

The Transport Accident Investigation Commission said pilot Lance Hopping was a long-term cannabis user and a post-mortem examination found the drug in his system.

Chief commissioner John Marshall said two witnesses saw Hopping smoking a substance on the morning of the accident and forensic tests showed no indication he had inhaled tobacco.

Marshall also noted there were no maintenance issues with the balloon and the weather was calm before it crashed near the town of Carterton, north of Wellington, as relatives of those on board watched in horror.

He said it appeared “highly likely” that Hopping, 53, smoked cannabis before the flight.

“Having considered all the evidence, the commission found that the accident was caused by errors of judgement by the pilot, and the possibility that the pilot's judgement was impaired by the use of cannabis cannot be excluded,”Marshall told reporters.

He said Hopping made a mistake in taking the balloon below the level of the power lines, then when it began drifting towards them he applied the burners to try to climb over them, instead of descending as quickly as possible.

Marshall called for tighter regulations in all sectors of the transport industry, including random testing. “It is totally unacceptable for anyone in a safety-critical transport role, such as a pilot, to be working while impaired by a substance, whether legal or not,” he said.

“Cannabis has both short and long-term impact on judgement, decision-marking, and reaction time depending upon the person, the quantity, and the frequency of use.”Transport Minister Gerry Brownlee said his department was considering the recommendations and wold report back to cabinet early next year.

The 10 passengers who died on the flight with Hopping were five couples from the Wellington region.

It was New Zealand's worst aviation disaster since 1979, when an Air New Zealand jet crashed into Mount Erebus in Antarctica, killing 257 people.