By Byron Kaye
PERTH, Australia, April 22 (Reuters) - A tropical cyclone heading south over the Indian Ocean caused the air search for a missing Malaysian jetliner to be suspended on Tuesday, as a U.S. submarine drone neared completion of its undersea search without any sign of wreckage.
The daily air and sea sorties have continued for a week since Australian authorities said they would end that component of the search for Malaysia Airlines Flight MH370, which disappeared on March 8 with 239 people on board.
But on Tuesday, hours after authorities said up to 10 military aircraft and 10 ships would join the day's search, they said the air search had been suspended because of poor weather as a result of Tropical Cyclone Jack.
"It has been determined that the current weather conditions are resulting in heavy seas and poor visibility, and would make any air search activities ineffective and potentially hazardous," the Joint Agency Coordination Centre said in a statement.
The ships involved in the day's search about 1,600 kms (990 miles) northwest of the Australian city of Perth would continue with their planned activities, the centre added.
The setback occurred as the $4 million U.S. Navy submarine Bluefin-21 was scheduled to complete its mission as soon as Wednesday with the search officials confirming the device is yet to find any sign of wreckage.
The authorities have turned up no conclusive evidence of the aircraft's ultimate location but believe sonar signals, or "pings", detected in the Indian Ocean search area several weeks ago may have emanated from the plane's "black box" recorder.
But after more than a week of daily sweeps of the largely unmapped stretch of ocean floor some 4.5 kms (2.8 miles) deep and 2,000 kms (1,200 miles) northwest of the Australian city of Perth, the drone is yet to produce any sign of wreckage, officials said on Tuesday.
On April 18, the Perth-based Joint Agency Coordination Centre told Reuters that the Bluefin's search of the target area, a circle with a 10 kms (6.2 mile) radius, would likely end in as little as five days.
As the remote controlled submarine was expected to complete its ninth mission on Tuesday, four days after the coordination centre gave the five-day timeframe, the centre confirmed that it had covered about two thirds of its target search area and had found "no contacts of interest".
The dawning prospect of the Bluefin-21, initially seen as the search's most promising aid, completing its mission without a trace of the missing aircraft has authorities under pressure to determine which strategy to take next.
The daily search involving some two dozen nations is already shaping up to be the most expensive in aviation history. (Editing by Michael Perry)