Weeks of vitriol, conspiracy theories and an informal travel boycott directed at Malaysia by Chinese people upset over the lost jetliner have prompted Beijing to move into damage control to protect the countries' normally friendly relations.

Malaysia Airlines Flight 370 disappeared on March 8, carrying mostly Chinese passengers, pitching Kuala Lumpur into a high-profile, unprecedented and so far unsuccessful search for the jet.

Facing frustration at home, the Chinese government was forced to take up its citizens' case with Kuala Lumpur, publicly calling on the government to share more information and speed up the search. That upset many in Malaysia, the government included.

Now Beijing is distancing itself from the shriller criticisms, highlighting the delicate line it must walk in supporting the families without inflicting lasting damage to relations with an important neighbor.

Speaking to Malaysian reporters Wednesday, Chinese Ambassador Huang Huikang called some of the relatives' viewpoints "radical," ''extreme," ''somewhat irresponsible" and not representative of China's view. He emphatically stated Beijing's support for Malaysia's handling of the crisis.

"We never said China was angry about the current situation and we never said we were dissatisfied about the progress so far that has been made," Huang said. "We are good friends. We are partners. This is just an incident which will never affect our good relations."

Officials have warned that the investigation may never answer why the Boeing 777 vanished while flying from Kuala Lumpur to Beijing with 239 people aboard, 153 of them Chinese. A dearth of information has plagued investigators from the moment the plane's transponders, which make the plane visible to commercial radar, were shut off early in the flight.

The Chinese relatives have become the human face of the tragedy, their anguish and despair over the uncertain fate of their loved ones illustrating the emotional toll of the plane's disappearance.

That despair has sometimes turned into anger, with family members tossing water bottles at the Malaysian Embassy in Beijing during a rally last week, heckling Malaysian officials as "liars" and staging walk-outs from meetings. Anger has spilled over to the wider public, with celebrities criticizing Malaysia and travel companies announcing boycotts of Malaysia Airlines flights.

An American woman whose boyfriend was on the missing plane said the way some Chinese relatives were campaigning was not helpful.

Sarah Bajc, an expatriate teacher, said pressuring Malaysia to devote staffers and resources to the Chinese relatives "is like having baby sitters for a bunch of spoiled brats throwing a tantrum."

"All the Chinese are doing is hurting themselves," she said. "They're interfering with the investigation. They're losing face. They're losing confidence in front of the world's eyes."

Malaysia's Defense Minister Hishammuddin Hussein has responded to the Chinese criticism and the relatives' outpouring of anger by defending his country's efforts, saying history would judge the country well, as well as with reminders that 50 Malaysians also were on the missing plane.

China's Communist Party leaders need to show they can protect their citizens both at home and abroad, and the government has been eager to show support for Chinese relatives of passengers, no matter how shrill their criticism and accusations toward Malaysia.

At the same time, the government has sought to maintain its good ties with Malaysia, endorsing the Southeast Asian nation's leadership of the search and pledging Beijing's help with ships, planes and satellites.

The tragedy has "caused a strong backlash among the Chinese public who are displeased that the Malaysian government and airline have not performed their duties properly," said Zhao Gancheng, director of Southeast Asian Center of Shanghai Institute of Foreign Studies. "But the Chinese government does not want this accident to affect the bilateral relationship. That's the bottom line."

Many Chinese relatives are skeptical of accounts by the Malaysian government and have accused it of hiding the truth or even being involved with the plane's disappearance. They were also infuriated when Malaysia concluded without any physical evidence that the jet went down in the Indian Ocean.

Malaysia has been largely patient and accommodating of the Chinese relatives' requests, hosting scores of family members in hotels in Beijing and near Kuala Lumpur and organizing high-level briefings with experts for them, most recently on Wednesday. Still, many relatives are unsatisfied.

"The Malaysian government has been hiding and not forthcoming. They don't even have a direction (in which to search). How can we expect them to find the wreckage?" Jane Bai, whose mother was on the plane, said in Beijing after Wednesday's briefing.

In China, people are generally distrustful of authority and more prone to believe conspiracy theories, or that people in charge are hiding things, said Zhan Jiang, a journalism professor at the Beijing Foreign Studies University.

"My view is that so much time has passed, they should cool down a little and deal with it more calmly and not just put this kind of pressure on the other side," Zhan said.


Associated Press writers Ian Mader and Didi Tang and researcher Zhao Liang contributed to this report from Beijing