Police in Slovakia have revealed that "suspects from Austria" tried to buy ammunition there in the summer and that Austrian authorities were tipped off.

Four people were fatally shot and 23 others wounded when a gunman went on the rampage in the centre of Vienna on Monday night.

It has since emerged he had been released early from a jail sentence for trying to join jihadists in Syria.

Reports suggest his trip to buy bullets failed as he had no gun licence.

According to German media, the 20-year-old, who was shot dead by police, travelled to neighbouring Slovakia in July to buy ammunition for a Kalashnikov AK-47 assault rifle but returned empty-handed. 

Slovak police confirmed that they had passed the message on to their Austrian colleagues immediately, adding they would not comment further. 

Read more: BBC News