DUBAI, Oct 20 (Reuters) - Five people were killed and four injured in a blast inside a Syrian army ammunition depot alongside the Homs-Hama road in the centre of the country, Iran"s state-run TV channel Al-Alam said on Wednesday. The explosion happened during a routine maintenance operation inside the depot, it said. Iran, a main backer of Syrian President Bashar al-Assad, has a military presence, directly and through proxy militias, across Syria including the region of Homs. The report did not indicate the nationality of the casualties.