The challenge will be to keep the convoy moving forward without breaking up.

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But the convoy arrived in Kabul itself only after dark, and certainly without fanfare.

BBC: Local Afghans and a Russian guard

The governor, his driver and his bodyguards survived the blast without injury, but the explosion is said to have killed bystanders or those in cars following the convoy.

BBC: NEWS | Europe | Three killed in Turkey bomb blast

Mr Hillo said that the operation "could not have happened without the Syrian government", which had agreed to issue landing permits for UN planes and also to allow the convoy to proceed to Azaz.

BBC: UN aid reaches Syria rebel-held northern area of Azaz