The UK and France have announced new measures to prevent "undocumented migrants" entering the Channel Tunnel by tackling the criminals who smuggle them to Calais and across the Channel.
The plans include the creation of a joint police operation aimed at tackling the people-smugglers who profit from the desperation of those trying to reach British shores.
Operation Stack remained in force on the M20 today because of the disruption in Calais and heavy traffic heading towards the coast.
The operation has been used recently because of disruption to Eurotunnel services caused by migrants trying to reach the UK and reduced ferries from Dover to Calais due to strikes in France.
Freight traffic is held in two lanes on either side of the carriageway, one for tunnel traffic and one for port traffic.
Vehicles are released from the queue whenever a train or ferry is ready to depart.
Lorry drivers have to collect a ticket while in the queue to be allowed to continue to the continent.
Non-freight traffic has to follow diversions around the sections of the M20 that are closed for queuing lorries.
A joint police operation has been launched to target people-smugglers who profit from the desperate migrants trying to reach the UK.
Calais' Mayor has accused Cameron of treating the region with "contempt" - and called on authorities to open the border unless help is given
More fencing and extra sniffer dogs have been sent from the UK to Calais in a bid to curb migrant incursions into Britain.