Millions of pounds of drugs destined for NHS hospitals have had to be destroyed after Calais migrants broke in to the lorries carrying them to Britain, it has been claimed.

Hauliers say they have been forced to ditch the medication because it is supposed to be transported in a secure environment and could be contaminated by the presence of an intruder.

Transport bosses fear they will have to start importing drugs - including cancer treatments - by plane if the migrant crisis at the French port continues.

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Break-in: Would-be migrants at Calais have been able to get in to the back of lorries travelling to Britain

For weeks, would-be asylum seekers desperate to get to Britain have been attempting to break in to the back of lorries so they can smuggle themselves through the Channel Tunnel.

Hauliers have repeatedly complained about the disruption to their work caused by the migrants and by wildcat strikes from French ferry workers.

On one occasion, a major drugs company had to destroy £2.5million of medication when it was contaminated during transit, according to the Freight Transport Association.

The organisation, which represents British haulage companies, says that just a single person breaking in to a truck can make medicine potentially unsafe.

Risk: A group of migrants trespass on to the tracks of the Channel Tunnel in a bid to reach the UK

Protest: A group of activists and migrants held a demonstration calling for open borders yesterday

Deputy chief executive James Hookham told the Daily Star Sunday: 'Even very high security vehicles are being compromised. I've been told the cost is hundreds of thousands of pounds.'

He added: 'The goods may look fine on the outside and the inner packaging but who is going to make that call to say if they are safe once contaminated?

'This disrupts the normal flow of needed drugs. It is not good if you have a shortage of important NHS drugs.

'Inside the trucks there will be a range of different drugs and equipment, from bandages and bedpans to highly needed cancer drugs.'

Desperate: Migrants queuing for charity food hand-outs at the entrance to the 'Jungle' camp in Calais

A spokesman for NHS England declined to comment on the issue.

The long delays at both Calais and Dover - with lorries forced to queue for house on the M20 - have also affected the delivery of fresh food and white goods which have been contaminated by the break-ins.

The authorities have moved to reinforce security at Calais and the Eurotunnel terminal in Coquelles following a mounting political row over migrants' repeated attempts to storm the Tunnel and enter Britain.