BEIJING, March 11 -- The international community strengthened rescue and search forces for the missing Malaysian plane on Tuesday, but no substantive clues have been found so far.

China sent its second naval vessel Jinggangshan to the target sea area on Tuesday morning and formed a unit with Mianyang, which arrived Monday, and promptly started searching operations for the missing Malaysia Airlines Flight MH370.

According to the Chinese navy, another two warships are expected to reach the area on Tuesday afternoon and Wednesday morning, respectively, and a depot ship has been ordered to prepare for moving into the Gulf of Thailand to replenish the searching vessels.

The Boeing 777 aircraft suddenly vanished from radar early Saturday morning while carrying 227 passengers and 12 crew members from Kuala Lumpur to Beijing. Among the passengers, 154 are Chinese.

In order to handle the aftermath of the missing Malaysia Airlines flight, a 13-member Chinese working group, composed of officials from the Ministry of Foreign Affairs, Ministry of Public Security, Ministry of Transport and Civil Aviation Administration of China, arrived at Kuala Lumpur International Airport Monday night.

Chinese President Xi Jinping has ordered an all-out search and rescue effort. Several Chinese civilian ships have already been sent to assist the mission.

Dozens of ships and planes from around 10 countries are scouring the waters around Flight MH370's last known location, but no solid clues have been found so far.

The U.S. Navy said Monday it has dispatched one more Arleigh Burke-class guided-missile destroyer, USS Kidd, to join the USS Pinckney in the search efforts.

The USS Kidd brings its two MH-60R Seahawk helicopters designed for search and rescue, as well as anti-submarine warfare, anti-surface warfare, surveillance, communications relay, naval gunfire support and logistics support, the U.S. Navy said.

Other countries, including Thailand and New Zealand, also sent search and rescue missions to the targeted sea area. A Thai navy boat was searching the lower part of the Andaman Sea off southern Thailand, while a New Zealand air force P3 Orion aircraft is en route to join the search.

Vietnam's search and rescue mission also pledged on Tuesday to further extend the search area in cooperation with other involved countries though the chances of locating the missing passenger plane are remote.

Vietnam confirmed that a life jacket-like object, spotted at sea by a commercial plane from Hong Kong earlier Monday, turned out to be unrelated to flight MH370.

Also on Monday, Malaysia said tests on a sample of the oil slicks found off the eastern Malaysia coast revealed that it was not from the missing flight, and the two passengers on board with false European passports, an Austrian and an Italian one, are not with Asian appearance.

Malaysian local media reported earlier Monday that one of the two suspects who used stolen passports has been identified. Inspector General of Police Khalid Abu Bakar said the man has been identified based on CCTV footage gathered from Kuala Lumpur International Airport.

Meanwhile, Christian Kozel, the 60-year old Austrian whose stolen passport caused him to be registered on seat number 26 of the missing flight, gave his first interview on Monday.

Kozel, retired massage therapist living in the Austrian city of Salzburg, said his passport was stolen two years ago at the Phuket International Airport in Thailand during a moment of inattention.