Only two bodies had so far been identified so far in the course of the investigation.
The 21 new victims included one German, 16 Dutch, two Malaysians, a Canadian and a Briton, the Dutch justice ministry said in a statement.
Dutch Prime Minister Mark Rutte said that the search for body parts at the crash site was being suspended due to escalating clashes between Ukrainian forces and pro-Russian separatists.
Two military transporters – a Dutch Air Force C-130 and an Australian C-17 Globemaster – arrived in the southern Dutch city of Eindhoven around 1pm GMT , carrying 142 police experts from the Netherlands, Australia and Malaysia, the Dutch news agency ANP reported.
On board the C-130 were 28 Dutch, 10 Australians and five Malaysian investigators, while the Australian plane carried 54 Dutch, 30 Australian, 15 Malaysians and five sniffer dogs.
The Malaysia Airlines 777 exploded over Ukraine on July 17, killing all 298 on board, 193 of them Dutch, with the West accusing Russia-backed separatists of shooting it down.
Over 220 coffins have been flown back to the Netherlands, which has been tasked with identifying the bodies.