The level of security at Marseille's Stade Velodrome was again open to question after police failed to prevent around 200 Hungary fans from moving from one end of the ground to the other ahead of Sunday's (AEST) game with Iceland.

The group, wearing black t-shirts, made a very obvious move to leave the north stand, breaking through a limited cordon before racing along the Tribune Ganay.

When it reached the far corner, it was met by a group of around 20 stewards who held it back for around five minutes, presumably until back-up from the police arrived.

It failed to materialise and the group, seemingly in a co-ordinated move, burst through before joining its compatriots in the south stand.

One fan attempted to cross via a piece of tarpaulin and fell approximately 10 feet on to the concrete floor.

Only once the fans were safely across did the police attend the scene.

A loud firecracker was also set off from the Hungary end.

It is the second major incident to occur in Marseille after Russia fans burst through a flimsy cordon to attack England supporters at the conclusion of last Sunday's (AEST) 1-1 draw.

Russia was handed a suspended disqualification from the tournament by UEFA, which is also investigating after Croatia fans hurled fireworks on to the pitch during its game with Czech Republic, forcing the game to be halted momentarily before it ended in a 2-2 draw.