Family members of passengers on board flight MH370 have marched on the Malaysian embassy in Beijing demanding answers, after authorities said they had concluded the missing plane crashed in the remote Indian Ocean with the loss of all 239 people on board.

More than two weeks of confusing and sometimes contradictory briefings have left relatives of more than 150 Chinese citizens on board deeply suspicious about the search and investigation.

The well co-ordinated protest followed Monday night's announcement by the Malaysian prime minister and Malaysia Airlines that all evidence suggested the plane had crashed into the southern Indian Ocean.

The Malaysia Airlines group chief executive officer, Ahmad Jauhari Yahya, told reporters on Tuesday: "My heart breaks to think of the unimaginable pain suffered by all the families. There are no words which can ease that pain. Everyone in the Malaysia Airlines family is praying for the 239 souls on MH370 and for their loved ones on this dark day."

Asked whether he would resign, he said it was a personal question that he would consider later.

Some family members have said they cannot accept the conclusion until they see physical evidence of a crash. But on Tuesday gale force winds and heavy rains forced Australian authorities overseeing the search to call off their efforts.

On Tuesday about 200 people marched from the Beijing hotel where were staying to the Malaysian embassy, wearing T-shirts reading "pray for MH370" and carrying printed signs saying "Tell us the truth" and "MH370, don't let us wait too long!"

The mood was sombre and mostly quiet as the crowd made its way along the main road, although periodically they chanted slogans including "The Malaysian government cheated us."

Steve Wang, who said he had a family member on the plane, accused Malaysian officials of not respecting the families. He said the relatives had marched to the embassy after they were told the ambassador would meet them at the hotel but failed to appear.

Several of the protesters threw bottles of water towards the building as they chanted for diplomats to come out and take their statement, calling them "beasts". They were bussed back to the hotel to meet the ambassador after a two-hour protest.

Chinese authorities – which normally crack down on street protests – facilitated the march, closing off to traffic the main road taken by protesters. Despite heavy security, they allowed them to protest outside the embassy for two hours.

Many of the families learned the news they had dreaded via a text message warning them: "We have to assume beyond all reasonable doubt that MH370 has been lost and none of those on board survived."

Relatives of passengers on the missing flight march to the Malaysian embassy in Beijing. Photograph: Rolex Dela Pena/EPA

At a news conference in Kuala Lumpur, airline officials defended sending a text message as a last resort to ensure that family members did not hear the news first from media if they could not be reached by a phone call or in person.

But the fact the message was sent in English only and that the families gathered in Beijing were not briefed en masse added to the anger of relatives.

Chinese state media said a senior member of the state council was on his way to meet family members on Tuesday – the first senior official to do so since the plane vanished. High-ranking leaders – often the premier or the president himself – are usually quick to make consolation visits to those involved in high-profile tragedies.

Malaysian authorities have said they believe the diversion of the plane – less than an hour after take-off from Kuala Lumpur on 8 March – was deliberate. But while investigators are looking into possibilities including hijacking and sabotage, they have not ruled out other explanations such as technical problems.

The communications systems stopped working or were shut off at around the time it turned west, away from its course to Beijing, and recrossed the Malay peninsula.

Experts say there is little hope of learning how and why the Beijing-bound flight diverted from its route and ended in the ocean unless the wreckage can be found.

"This is a mystery and until we recover and positively identify a piece of debris everything is virtually speculation," the Australian defence minister, David Johnston, told reporters at the RAAF Pearce air base north of Perth on Tuesday.

He added: "The challenge of flying to such a remote region and conducting search operations cannot be overstated. With eight hours of flying to and from the search region, the fleet of P3 Orion aircraft and other military aircraft have only a precious few hours to scour the search tracks they have been given."

Air Marshal Mark Binskin warned: "We're not searching for a needle in the haystack, we're searching for where the haystack is."

The Chinese government has already promised to dispatch more vessels to the remote search zone – around 2,500km (1,500 miles) south-west of Perth – to assist the operation.

A government source told Reuters that Malaysia would lead the investigation, but hoped other countries, especially Australia, would play a major role.

Final confirmation of the disaster came after 17 days and was based on unprecedented analysis of "ping" signals sent to a satellite as the plane continued flying after disappearing from radar when its main locating beacons stopped operating and it veered off course between Malaysia and Vietnam.

The Chinese deputy foreign minister, Xie Hangsheng, has demanded Malaysia hand over all relevant satellite analysis showing how it reached its conclusion about the aircraft's fate.

As the search for wreckage continues a race is under way to find the black box recorders from the plane. The cockpit voice recorder and a data recorder emit a high-pitched ping underwater for at least 30 days after a crash.

The Australian and US navies are sending equipment to the search area to hunt for the signals – the Americans dispatching a "towed pinger locator", a cylindrical microphone that is towed behind a ship in a grid pattern and can detect a signal up to two miles away. The Australian navy said it was deploying vessels equipped with acoustic detectors capable of picking up the audible beacon.

"We've got to get lucky," said John Goglia, a former member of the US National Transportation Safety Board. "It's a race to get to the area in time to catch the black box pinger while it's still working."