A former head of the Royal Navy has warned that Britain is at risk from terrorists and traffickers because of the lack of boats that patrol UK waters.
Lord West described the situation as a "complete mess" as three Border Force vessels are left to patrol 7,700 miles of coastline, the Daily Mail reports.
This follows the deployment of one to the Aegean Sea to help with the migrant crisis and after aerial surveillance of Britain's shores was scrapped in January.
Lord West told the newspaper: "We are taking a calculated risk with our own territorial waters.
"Already we have seen these illegal immigrants and I don't believe there aren't clever traffickers using the smaller ports to send them and I'm sure terrorists are aware of the route too.
"We need to get a grip on this. We are taking a gamble that nothing will ever happen in our seas and that is a risky view to take given the dangerous world we are in."
Two Border Force cutters, HMC Protector and HMC Seeker, were deployed to the Mediterranean along with the Royal Navy ship HMS Bulwark last May.
Civilian vessel VOS Grace was sent to the Mediterranean last November.
Lord West's warning comes as 18 Albanians - including two children - and two British people were rescued from the English Channel after their inflatable boat began to sink on Saturday night.
Last month he pressed the Government over border security amid concerns the UK's at-sea defences were "in a very parlous state".
Speaking during an urgent question on the budget of the Border Force, Lord West said: "Our coastline outside the major ports is highly vulnerable.
"Would the minister confirm as we have sent coastguard cutters to the Mediterranean and because of defects, that we only have two coastguard cutters to look after our coastline from the Tyne round to Cornwall.
"And that we have now cancelled the airborne surveillance programme, which was able to indicate targets of interest, such as illegals coming into the country, to those cutters, because if that is the case we are in a very parlous state."
Responding, Home Office minister Lord Ahmad said he could not give operational details about the Border Force, but insisted there was sufficient capability and funding in place to maintain a presence in UK waters.
John Vine, who was independent chief inspector of borders and immigration until 2014, said a series of warnings about the threat had failed to result in "sufficient resources" being devoted to the issue if lives were not to be lost.
"In the context of small ports, we just don't know the extent of this," he told BBC Radio 4.
"But I think it is reasonable to assume that this is something that might have been happening and if this is now the start of a new trend we certainly need to gather the intelligence and the resources to nip it in the bud."
He said he found the issue "wasn't a major priority" when he raised concerns in the past.
"That is entirely reasonable: if an organisation has limited resources, it has to prioritise where its enforcement activity is," Mr Vine said.
"But clearly if this is now the start of something new, then really that ... needs to be reassessed and resources need to be put in."
He added: "We have seen the tragedies that have occurred in the Mediterranean.
"I am not a nautical person but I would have thought crossing the Channel - with all the hazards in terms of cross-Channel traffic as well as the weather and the sea conditions - are going to mean there is an equal chance of people losing their lives unless this is stopped."