BEIJING, April 2 -- The search for Malaysian flight MH370 continued Wednesday, while Chinese Premier Li Keqiang and Australian counterpart Tony Abbott agreed to continue all-out efforts to find the missing plane.

Efforts continued Wednesday with the first aircraft, a Chinese Ilyushin IL-76 plane, departing for the search area in the southern Indian Ocean west of Perth at 6 a.m. local time, the Joint Agency Coordination Center (JACC) said.

An Australian E-7A Wedgetail airborne early warning and control aircraft assisted in Wednesday's mission. The Wedgetail spy plane, capable of deconflicting air space in the search area, will act as an air traffic controller.

The Australian defense vessel Ocean Shield, with a black-box detector on board, is also on its way to the region.

About 10 aircraft and nine ships are involved in the operation, which faced broken cloud, sea fog and isolated thunderstorms Wednesday.

Chinese ships focused their search on a rectangle-shaped area covering 220,000 square km with its center at about 29 degrees south latitude and 101 degrees east longitude, northeast of Tuesday's search area, Jiang Long, captain of the Chinese vessel Haixun 01, said.

Four Chinese military vessels have been assigned to the southern part of the new area, while Haixun 01, Nanhaijiu 115 and Donghaijiu 101 will search in the northern patch, Xinhua has learned.

Haixun 01 had found and ruled out 12 suspicious objects, and nothing related to the missing plane had been found so far, Jiang said Tuesday.

The Malaysian government confirmed Wednesday a British nuclear submarine would join the search.

On the same day, Abbott updated Chinese Premier Li in a phone hook-up Wednesday with the latest developments in the mission, as well as the ongoing investigation.

Li appreciated the Australian authorities' efforts.

He said China would continue to cooperate and communicate closely with the relevant agencies in Australia, Malaysia and other parties to make all-out efforts as the search continued, while at the same time conducting a thorough investigation, Li said.

Abbott spoke highly of China's input, saying his country would work with China, Malaysia and others to better communication and cooperation, and step up its search efforts to the best of its ability.

Meanwhile, Malaysian Inspector General of Police Khalid Abu Bakar said Wednesday all 227 passengers on board the missing flight had been "cleared" of links to hijacking, sabotage and psychological or personal problems by the police.

He said the cabin crew, including the pilot and the co-pilot, were still being investigated in these four areas, noting police would not release any findings for fear of jeopardizing the ongoing probe.

Malaysian government officials briefed Chinese families on the investigation and pledged to continue doing everything to find the missing craft, a statement from the Malaysian Transport Ministry said Wednesday.

A special briefing session was held for the Chinese relatives of those on board MH370 at Hotel Bangi in Putrajaya, the administrative center of Malaysia.

The briefing session was moderated by the Malaysian Prime Minister's Special Envoy to China Tan Sri Ong Ka Ting.

The briefing was also telecast live to other Chinese families gathered in Beijing.

"China had more nationals on board MH370 than any other country. Malaysia recognizes its duty to provide the government of China with verified information, which it can then use to brief the Chinese relatives of those on board MH370," a statement said.

Malaysia also sent a delegation to Beijing led by Deputy Foreign Minister Dato' Hamzah Zainudin, who met Chinese counterparts Vice Foreign Ministers Zhang Yesui and Liu Jianchao.

Attempts are being made by the Malaysian government to reduce tensions with the Chinese families, who have expressed dissatisfaction with the steps taken by the Malaysian government since the flight went missing more than 20 days ago.

Malaysian Prime Minister Najib Razak was scheduled to arrive in Australia later Wednesday to meet Abbott and visit the headquarters for the search operations.