However, terrorism expert Hans-Jakob Schindler of the Counter Extremism Project said he did not find that explanation convincing, saying: 'The personnel links to the Hamas leadership are too close.'

Schindler said Hamas' growing weakness following the war with Israel could increase the risk of attacks abroad.

'Hamas' weakness is not a good sign for Europe in itself,' he added.

He said terrorist organisations seek publicity to demonstrate their continued relevance.

 Schindler further suggested that an attack in a European city or on a cruise ship in the Mediterranean would generate global attention while placing political pressure on countries viewed as supporters of Israe