PERTH: A robotic mini-submarine deployed to unprecedented depths underwater to hunt for the crashed Malaysian airliner has searched nearly two-thirds of the focused area of the Indian Ocean floor, as it ended its eighth mission on Monday with still no sign of any wreckage of the plane.

Autonomous underwater vehicle Bluefin-21 , a US Navy probe equipped with side-scan sonar, has focused the search on an area where four acoustic signals were detected, leading authorities to believe that the missing Malaysia Airlines Flight MH370 's black box may be located there.

"This morning, Bluefin-21 AUV completed mission eight in the underwater search area. Bluefin-21 has searched approximately two-thirds of the focused underwater search area to date," Perth-based Joint Agency Coordination Centre (JACC) leading the search said in a statement.

"No contacts of interest have been found to date," it said, as the search entered its 45th day today.

Bluefin-21 AUV's ninth mission will commence later today. Up to 10 military aircraft and 11 ships will assist in today's search for the Boeing 777-200 that went mysteriously missing on March 8 with 239 people on board, including five Indians.

The Australian Maritime Safety Authority has planned a visual search area totaling approximately 49,491 sq kms for today's hunt. The centre of the search area lies approximately 1,741 kilometres north west of Perth.

Weather forecast for Monday has conditions deteriorating, particularly in the north of the search area, as tropical cyclone Jack continues its track southwards. Wide spread showers are developing with isolated thunderstorms to the north and east south-easterly winds, the statement said.

The focused underwater search area is defined as a circle of 10km radius around the second Towed Pinger Locator detection which occurred on April 8.

Finding the black box and the wreckage are crucial to know why the Beijing-bound plane veered off from its route and mysteriously vanished after taking off from Kuala Lumpur.

The mystery of the missing plane has continued to baffle aviation and security authorities who have so far failed to trace the aircraft despite deploying hi-tech radar and other gadgets.

Meanwhile in Kuala Lumpur, a Malaysian official said on Sunday that the families of the passengers and crew of flight will receive financial assistance from Malaysia Airlines to ease their burdens.

Deputy foreign minister Hamzah Zainuddin, who heads the sub-committee focusing on the next-of-kin, said the assistance would come solely from Malaysia Airlines, with the government only stepping in to bear some of the costs if there is a need for it.