Criminal investigators probing the destruction of Malaysia Airlines flight MH17 have received additional radar information from Russian authorities.
The Dutch national prosecutor's office had previously expressed irritation that Russian-supplied radar data had not been provided in the internationally-accepted 'Asterix' format developed by Eurocontrol.
But the office states that, following a supplementary request for assistance, the additional radar information "should now be" in the required format, and will be "examined in depth" by the joint investigation team.
Radar data has been a contentious issue in the probe into the loss of the Boeing 777-200ER, which was shot down by a surface-to-air missile over eastern Ukraine in July 2014.
Russian authorities had originally supplied only video footage of processed radar information, rather than raw data, to the inquiry. None of the information supplied showed the missile in flight.
The Dutch-led investigation, which identified a launch site in eastern Ukraine in late September last year, stated that – because a radar rotates in its surveillance sweep – the absence of the missile on radar images "did not mean the [weapon] had not flown".
"It may be so that the radar was just working on the [opposite] side of its scanning [sweep] at the moment the missile was launched," it adds.
Russian radar data subsequently handed over in October was not in the Asterix format and, although software had been provided to aid analysis of the data, investigators were hampered by lack of manuals and the fact that the software was in the Russian language.
The format of the information meant the probe could not determine, with certainty, what the images showed and whether they were authentic.
"Data that had been handed over showed less than if the data had been submitted according to the Asterix format," says the prosecutor's office.
Using the internationally-recognised Asterix standard would have enabled investigators to "guarantee the integrity" of the radar system, it adds.
"It would have enabled us to gain better insight into possible additional detection of objects which had not appeared on the radar screen of the air traffic controller," says the office, "but would have been collected by the radar system and stored in the subsystems."