Ironically, the Scotsman sidebar leads to today's report that the investigators have still not identified the explosives used in the bombings. Likewise the FT cites unnamed intelligence sources - that appear to be just plain wrong about this.
The reality is, that poring over the contradictory press reports just illuminates how much noise there is propagated in the press, and how hard it is to discern the signal.
Why he would do so falls into the realm of the political... I'm curious however if "Balkans" is a codeword for "Czech Republic".
Pax Night and day you can find me Flogging the Simian
A lot of it was sold to Libya during the Communist era, when the Arab states were "friendlies".
Whilst he may have been in London assisting the investigation - he's not a ground-floor forensics investigator; and his language was hedged in such a way in the article for it to be clear that it was a speculative take.
There's also the prior event paradigm to take into account: seeing events in London in the light of events in Madrid, whilst "natural" - I certainly did to begin with - often leads down the wrong track. I doubt that Chaboud is any more immune to this than most of us - and I would certainly characterise him as someone likely to have a political agenda that he is seeking to advance.
I think that references to the Balkans would not include the Czech Republic. Specifically, I would guess that Chaboud is referring to the Former Yugoslavia or Albania, but I couldn't narrow it down any further than that. If he's referencing smuggled Balkan explosives then it's likely that he is making the obvious point that people and drug smuggling networks can also be used to smuggle explosives.