The majority of the Isil extremists who carried out the November 13 Paris attacks entered Europe while posing as migrants, Hungarian security officials have disclosed.

Seven of the attackers, who killed 130 people and left more than 360 others injured, slipped through Hungary's borders while posing as migrants.

It is understood that ten extremists in total were closely involved in planning and carrying out the massacre.

A handful of them are also understood to have taken part in the Brussels attacks last March, which claimed 32 lives.

According to Hungary's centre for counter-terrorism, the group of fanatics set up a "logistics hub" in the country in the summer of 2015 and began using the so-called Balkans route of eastern European countries to move fighters trained in Syria into Europe.

The disclosure comes amid a propaganda blitz in Hungary, which on Sunday began voting in a referendum on whether to accept the EU migrant quotas.

The country is expected to vote emphatically against the quotas, which would have seen them take in 1,924 asylum seekers.

Viktor Orban, Hungary's far-right leader, has repeatedly laid the blame for the migrant crisis - and the terrorists who took advantage of it - at the feet of Angela Merkel and her controversial "open door" refugee policy.