A robotic mini-submarine deployed to unprecedented depths of the Indian Ocean to hunt for the crashed Malaysian jet has searched nearly two-thirds of the focused area with no sign of any wreckage, as a tropical cyclone today threatened to hamper operations.

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.

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

Up to 10 military aircraft and 11 ships were part of today's search for the Boeing 777-200 that went mysteriously missing on March 8 with 239 people, including five Indians, on board.

Weather forecast was bleak for the search operations particularly in the north of the search area with Tropical Cyclone Jack continuing its track southwards.

Widespread showers were expected 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 for knowing 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-technology radar and other gadgets.

Meanwhile in Kuala Lumpur, a Malaysian official said yesterday 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.