Missing Malaysia Airlines flight MH370 may have been deliberately flown west towards the Andaman Islands after it last made contact with air traffic control nearly one week ago, military radar-trafficking evidence now suggests, in a twist that Malay officials have said supports theories the plane might have been hijacked or sabotaged.

Sources told Reuters that the flight path of an unidentified aircraft, which investigators believe was MH370, followed a route with specific navigational waypoints, suggesting someone with aviation training was at the helm.

Separately the Wall Street Journal reported that the missing jet had transmitted its location repeatedly to satellites in the five hours after its last contact with air traffic control before abruptly shutting off, according to US military and industrial sources. It said it did not know the flight path to this point but noted that the US had moved surveillance planes into an area of the Indian Ocean 1,000 miles (1,600km) west of the Malayasian peninsula.

The last known position of MH370 was at 1.21am at 35,000 feet roughly 90 miles off the east coast of Malaysia, as the Boeing 777 with 239 people on board made its way towards Vietnam, en route to Beijing.

If the unidentified aircraft picked up on the military radar reported by Reuters is indeed the missing jet, then data suggests the 777 veered dramatically and deliberately westwards, heading northeast of Indonesia's Aceh province towards a navigational waypoint used for carriers headed towards the Middle East.

From there, plot indications show the plane zigzagged towards the Thai island of Phuket and then, at 2.15am, continued on northwest route P628, which would lead it towards the Andaman Islands and perhaps onward to Europe. Malaysian military officials have previously confirmed that an aircraft that could be MH370 was last seen on military radar at 2.15am some 200 miles off Malaysia's west coast.

"What we can say is we are looking at sabotage, with hijack still on the cards," a senior Malaysian police official told Reuters.

The revelations emerged the same day as reports that the aircraft's two communications systems were systematically shut down and that manual intervention was the probable cause.

According to two US officials who spoke to ABC News, the 777's data reporting system was shut down at 1.07am, while the transponder – which sends back information to civilian radar regarding performance, location and altitude – was turned off at 1.21am.

US authorities have since decided to move their search operation towards the Indian Ocean after an undisclosed suggestion that the plane may have crashed there. "We have an indication the plane went down in the Indian Ocean," a senior Pentagon official said.

The USS Kidd destroyer, which has helicopters aboard, will be moved to the western tip of the Malacca Strait, where it meets the Andaman Sea.

That most of the leads on the potential location, and fate, of the missing aircraft are coming from US authorities indicates that it is the Americans – and not the Malaysians – who know more than they are letting on. The fact that US investigators cannot divulge more may be due to the fact that they are merely assisting the Malaysian investigation and not leading it: per international protocols, the country where the missing aircraft was registered must lead the investigation.

While Malaysian police have spent the past week investigating whether any personal or psychological problems plaguing the crew or passengers may have had a role in the jet's disappearance, in addition to mechanical failure, hijacking or sabotage, Friday's revelations that the plane may have flown towards the Andaman Islands are the first real indication that foul play could be the cause.

At a press conference late on Friday afternoon, Malaysia's defence and acting transport minister, Hishammuddin Hussein, said authorities were investigating the possibility that the plane's communications systems had been deliberately shut down and said there were four or five possibilities as to why the they may have been turned off.

"It could have been done intentionally, it could be done under duress, it could have been done because of an explosion," he said. "That's why I don't want to go into the realm of speculation. We are looking at all the possibilities."

Hishammuddin confirmed that MH370's "whole passenger manifest", including crew, were being looked into and added: "If investigation requires searching the pilots' homes, it will be done."

Aviation experts from the UK, in addition to a team from Rolls-Royce – which manufactured the 777's engines – were due to arrive in Malaysia on Friday night to help with the investigation, the civil aviation chief, Azharuddin Abdul Rahman, said.

Some 57 ships, 48 aircraft and 13 nations are now taking part in the search and rescue mission, which has been expanded further east into the South China Sea and further out into the Indian Ocean. Indian officials confirmed to the Wall Street Journal that authorities had begun searching the 572 islands comprising the Andaman and Nicobar island groups using heat-seeking devices to help find the missing plane, and would likely extend the search to the Bay of Bengal.

"The challenge of looking over land is that the islands are covered in very dense forest and most of them are hilly," Colonel Harmit Singh told the Journal. "Nothing has shown up as of now."

Hussein said Malaysia was investigating all potential leads and said: "We want nothing more than to find the plane as quickly as possible. But the circumstances have forced us to widen our search."

Speaking at the daily foreign ministry press briefing in Beijing, spokesman Hong Lei would not be drawn on whether China believed the plane had flown for several hours or whther it had asked the US about the reports.

He added that China had asked Chinese commercial vessels to take note of any floating objects which might be connected to the missing flight. A subsequent comment suggested this applied to vessels in the Strait of Malacca.

The Chinese state news agency Xinhua reported on Friday evening that search vessel Haixun 31, which had been at work in the Gulf of Thailand, was heading to the Strait of Malacca to continue work there.