Some experts have questioned whether Arafat could have died of polonium poisoning, pointing to a brief recovery during his illness which is not consistent with radioactive exposure. They also noted he did not lose all of his hair.
But Professor David Barclay said neither fact was inconsistent with the findings.
Since polonium loses 50% of its radioactivity every four months, the traces in Arafat's corpse would have faded so far as to have become untraceable if the tests had been conducted a couple of years later, Professor Barclay said.
More top news
Police and emergency services are attending the scene.
Rebel-held east remains at risk while the pumping station supplying the western part of the city is once again in operation.
Police chief says the video can now be release without 'adversely impacting' the investigation.