By Jane Wardell
SYDNEY, March 9 (Reuters) - The disclosure that an underwater locator beacon battery in the flight data recorder of MH370 had expired could be key in legal action against Malaysia Airlines over the fruitless search for the jetliner, lawyers for families of the passengers said on Monday.
U.S. law firm Kreindler & Kreindler LP, which is representing around 20 families, said the expired battery was "potentially very significant" in determining compensation if it had hurt the search for the missing plane.
A 584-page interim report into the disappearance of the Boeing 777-200ER said the beacon battery for the flight data recorder had expired in December 2012 and was not replaced. The beacon is designed to send a signal if a crash occurs in water.
The oversight was blamed on a failure to properly update a computer system in the engineering department of Malaysia Airlines, Malaysia's Department of Civil Aviation said in the report released on Sunday, one year after the plane vanished during a flight from Kuala Lumpur to Beijing.
"This airline, which allowed its crew and plane to fly with expired batteries on critical equipment, continues to reject offering any kind of meaningful settlement to the families without them first proving the losses they suffered, without any actual evidence of a crash," Kreindler & Kreindler LP aviation attorney Justin Green said in an email to Reuters.
"The airline ... even more clearly now may be responsible for the unsuccessful search for this plane."
In January, Malaysia Airlines officially declared the disappearance of MH370 an accident, clearing the way for the airline to pay compensation to victims' relatives while the search for the plane goes on.
Investigators believe the plane, carrying 227 passengers and 12 crew, was flown thousands of miles off course before eventually crashing into the ocean off Australia.
The search along a rugged 60,000 sq km patch of sea floor some 1,600 km (1,000 miles) west of the Australian city of Perth has found nothing so far.
The search in this area, which experts believe is the plane's most likely resting place, could be wound up in May after Australia's deputy prime minister said last week discussions were under way between Australia, China and Malaysia on whether to call it off soon.
However, Malaysian Prime Minister Najib Razak and the Chinese government said they remained committed to the search. Most of the passengers were from China.
The interim report offered no definitive cause for the plane's disappearance, adding there was nothing suspicious in the financial, medical or personal histories of the pilots or crew.
"The disappearance of MH370 is without precedent, and so too is the search - by far the most complex and technically challenging in aviation history," Najib said in a statement. (Editing by Dean Yates)