The international hunt for the vanished Malaysia Airlines jet has been marked by mounting criticism about the pace of the investigation, whether information is being shared and whether Malaysian officials are reaching out to enough experts.

China has assailed Malaysia’s handling of the probe. Vietnam at one point suspended its search after it thought Malaysia was holding back relevant radar information. Indian officials said Sunday that they would suspend their search-and-rescue effort while Malaysian officials determine where they should be looking.

Meanwhile, the number of countries involved in the search has grown from 14 to 25, adding further complexity to the sprawling effort.

The antagonism reflects, in part, long-simmering tensions in the region. A number of countries involved in the search have been arguing in recent years over territories not far from where someone in the plane’s cockpit last contacted air traffic control.

Six nations involved in the search have argued over islands and sea and air lanes in the South China Sea: China, Vietnam, Malaysia, the Philippines, Taiwan and Indonesia.

New data has provided an arc of possible locations for Malaysian Flight MH370.

Just days ago, a dispute flared between China and the Philippines over a shoal in the South China Sea.

But the concerns about the search and investigation reflect more than long-standing tensions among Asian countries. In Washington, officials said they were frustrated because they think the FBI could be of substantial assistance. A team of FBI agents is ready to go to Kuala Lumpur, but their assistance has not been requested by the Malaysian government, the officials said, speaking on the condition of anonymity because of diplomatic sensitivities.

The most reproachful official comments during the disaster have come from China. Its Foreign Ministry has urged Malaysia to “step up their efforts and speed up their investigation.” And China’s leaders keep sending more assets and officials to aid the investigation — and ratchet up the pressure.

An editorial Sunday by China’s official Xinhua News Agency accused Malaysia of ­“dereliction of duty” and “intolerable” reluctance to share vital information.

Much of China’s urgency stems from the fact that 154 of the 239 people aboard were from China or Taiwan. But there’s also a history of bad blood between the two nations.

In recent years, China has aggressively entered what Malaysia considers its territorial waters.

That may partly explain Malaysia’s days-long reluctance in revealing that its military and radar operators failed to track the plane as it turned and flew above one of the country’s biggest cities.

The passengers and crew on MH370

“I believe Malaysia was defensive about this and embarrassed,” said Ernest Bower, a Southeast Asia expert at the Center for Strategic and International Studies. With many Malaysians viewing China as a growing threat, their failure on radar detection sends a “signal to China and other neighbors that they are not able to use their maritime and aviation domain awareness capabilities to full effect,” he said.

Malaysian authorities say they have been forthcoming. Defense Minister Hishammuddin Hussein has pointed repeatedly to the country’s eventual release of military radar data as proof that the government is prioritizing the search above national security concerns.

China has been accused of being similarly careful about revealing too much about its capabilities during the search. When China released satellite photos last week showing possible debris, some analysts noted the fuzzy, grainy quality and said China was hiding its true high-resolution capabilities.

On Sunday, Malaysia pleaded for many countries to share their satellite and military radar data along two new search paths that stretch northward from Thailand to Kazakhstan and southward into the Indian Ocean.

When asked how many of those countries have agreed to turn over such data, Hishammuddin declined to answer, acknowledging that there were national security concerns for many countries.

In India, military officials issued a statement Sunday saying that the country’s wide-ranging search and rescue effort in the Andaman Sea and the Bay of Bengal had been put on hold as “search operations have entered a new phase and strategy for further searches is being formulated.”

Syed Akbaruddin, a spokesman for the country’s Ministry of External Affairs, said Indian officials were told that in view of new information, Malaysia would be revising its requests for support. As of Sunday evening, the Indian search teams remained on standby.

Malaysia’s prime minister on Sunday called Indian Prime Minister Manmohan Singh to ask for “technical assistance in corroborating the possible paths of MH370,” Akbaruddin said. Singh said all help would be provided, Akbaruddin said.

Privately, though, some in ­India’s government and military were becoming frustrated by the confusing path the investigation has taken.

“Even at this stage, while they’re expanding the scope of the search, my observation as an analyst is that we should go back to square one and get more accurate information about the sequence of events and where and how the aircraft made its last movements,” said Uday Bhaskar, a retired naval commodore who is an international security analyst.

The United States and Malaysia share a fairly robust history of military cooperation.

Early on in the investigation, Malaysia welcomed the assistance of an American team from the National Transportation Safety Board and the Federal Aviation Administration. Malaysian authorities also have shared radar data with the U.S. military.

Annie Gowen in India and Sari Horwitz in Washington contributed to this report.