UK investigators are to start examining the flight data recorder from the downed Malaysia Airlines plane.
The Air Accidents Investigation Branch in Farnborough will start the process almost a week after the plane crashed in eastern Ukraine.
Whitehall sources, meanwhile, say information shows some evidence was tampered with at the crash site.
The sources said this included moving bodies and scattering the parts of other aircraft among the wreckage.
All 298 people on board flight MH17 were killed in the crash in Ukraine on 17 July.
They included 10 Britons on the flight from Amsterdam to Kuala Lumpur.
British accident investigators will attempt to retrieve data from the recorders following a request by authorities in the Netherlands.
The Dutch Safety Board, which is leading the investigation, said "valid data" had already been downloaded from MH17's cockpit voice recorder (CVR) which will be "further analysed".
The board said: "The CVR was damaged but the memory module was intact. Furthermore no evidence or indications of manipulation of the CVR was found."
The black boxes have been transported to the UK after pro-Russian rebels handed them to Malaysian officials this week.
The data recorder records technical information on the performance of the aircraft.
The other box takes down sounds such as pilots' voices and, potentially, an explosion.
A spokesman for the Department for Transport said data from the two devices would be downloaded and sent back to Dutch investigators.
Depending on damage to the black boxes the process should take about two days, the spokesman said.
Jonathan Sumberg, BBC transport reporter, said the British Air Accidents Investigation Branch (AAIB) was one of two "replay units" in Europe with the necessary equipment to listen to the cockpit voice recorder.
They are two devices - neither of them black - which are designed to survive a crash.
The flight data recorder records operating information from the plane's systems, storing a range of information such as altitude, airspeed, engine power and the pilot's use of the controls.
The cockpit voice recorder, as its name suggests, records sound in the cockpit and can be vital in determining what happened to a crashed aircraft.
BBC reporter Theo Leggett said the black boxes would be taken to a sealed room at the AAIB headquarters in Farnborough where the data would be downloaded.
He said the flight recorder could potentially confirm whether the plane had been hit by a missile.
However, he said information from the cockpit voice recorder could be "relatively limited" as the impact of the explosion "would have occurred pretty much without warning".
Former aircraft accident investigator Tony Cable also told the BBC it was unclear how much information would be recovered from the flight recorders.
"The cockpit voice recorder could conceivably record the sound of shrapnel hitting the aircraft from the missile, which is assumed to be the cause, possibly followed by the sound of the warhead then exploding," he said.
Whitehall sources also told the BBC that pro-Russian rebels are believed to have discussed plans to hand MH17's two black box flight recorders to Russia.
It is understood that some of these conversations were intercepted by Ukrainian intelligence; the information is considered to be "very persuasive".
Intelligence has also been obtained which strongly indicates that the plane was shot down by an SA-11 BUK missile launched from a separatist-held area in eastern Ukraine.
Western leaders have accused Russia of arming separatist rebels in Ukraine.
Russia has suggested Ukrainian government forces are to blame.
It comes as a group of MPs criticised the fact that UK licences to export arms to Russia had remained in place, despite the conflict in Ukraine.
Downing Street said the UK had not sold arms to Russia since March.
The UK and Dutch flags have been flown at half mast in Downing Street in memory of those who lost their lives.