Chinese ships are searching a new area in the Indian Ocean for a missing Malaysian passenger jet.

However, only rubbish unrelated to the plane has been taken from the sea so far.

The search for Flight MH370 entered its fourth week amid a series of false dawns over sightings of debris.

Australian authorities coordinating the operation moved the search 685 miles (1,100km) north yesterday.

The move came after new analysis of radar and satellite data concluded the Malaysia Airlines plane travelled faster and for a shorter distance after vanishing from civilian radar screens on 8 March.

A Chinese military aircraft had earlier spotted three suspicious objects today in the new search area about 1,150 miles (1,850km) west of Perth.

The Chinese navy vessel Jinggangshan, which carries two helicopters, reached the new search area early today.

"We're hopeful to relocate some of the objects we were seeing yesterday," Royal New Zealand Air Force Squadron Leader Flight Lieutenant Leon Fox told Reuters before flying out to the search zone on an Orion P-3.

"Hopefully some of the ships in the area will be able to start picking it up and give us an indication of what we were seeing."

The search is expected to focus on searching for plane surfaces, oil slicks and life jackets in a sea area of 2,665 sq.m (6,

Another four Chinese vessels and one from Australia are on the way but will not arrive until late tonight.

Malaysia says the Boeing 777, which vanished less than an hour into a flight from Kuala Lumpur to Beijing, was likely diverted deliberately.

However, investigators have turned up no apparent motive or other red flags among the 227 passengers or the 12 crew.

US officials close to the investigation said the FBI found nothing illuminating in data it had received from computer equipment used by MH370's pilots, including a home-made flight simulator.

The search has involved more than two dozen countries and 60 aircraft and ships but has been bedevilled by regional rivalries and an apparent reluctance to share potentially crucial information due to security concerns.

Two Malaysian military aircraft, which arrived in Perth today, are expected to join the search party for the first time tomorrow.

The Malaysian government has come under strong criticism from China, home to more than 150 of the passengers.

Relatives of the missing people have accused the government of "delays and deception".

More than 20 Chinese relatives staged a brief protest today outside the Lido hotel in Beijing, demanding evidence of the plane's fate.

"They don't have any direct evidence," said Steve Wang, who had a relative on the flight.

"(Their conclusion) is only based on mathematical (analysis) and they used an uncertain mathematical model. Then they come to the conclusion that our relatives are all gone."

Malaysia's acting Transport Minister Hishammuddin Hussein said his country was committed to seeing the investigation through to its final conclusion.