Britain has one of the strongest borders in Europe, the head of the EU's law enforcement agency has insisted.
Rob Wainwright gave the assessment as he defended the Border Force, which has faced claims that large stretches of the UK coastline are being left unpoliced.
The issue fell under the spotlight after 18 Albanians had to be rescued from an inflatable boat after it sank off the Kent coast at the weekend.
Immigration union officials warned Britain's coast is facing one of its greatest breaches from small boats and dinghies carrying migrants.
Criticism has also focused on the disclosure that just three cutter vessels are currently being used to patrol the coastline.
Mr Wainwright, the Welsh-born director of Europol, told the Press Association: "I think, as I'm sure the UK Border Force understands, it has to plug all gaps in the border and this is an example of how difficult it is sometimes to get the balance right.
"They've got finite resources like any other public-sector organisation. They have to make tactical decisions on a daily basis about where they target their resources.
"Normally those would be on the major port areas for obvious reasons and because of that, normally they are very successful by standards of other European countries in apprehending most illegal attempts to get into the country.
"When you are in the business of targeting your resources where intelligence takes you, then sometimes one or two things will slip through because you are looking elsewhere, for good reason."
He added: "It is worth pointing out that because Britain is an island, because Britain is outside the Schengen zone but also because it has information sharing arrangements with EU partners, it still has one of the strongest borders of any country in Europe.
"That is a consensus view right across Europe."
Europol is tracking more and more people-smuggling organisations across the continent, Mr Wainwright said.
"What I see, having a pretty good view of people smuggling right across Europe, is that Britain does its job most days very, very well," he added.
The director has previously warned that the UK's access to some systems it depends on to keep its people and borders safe could be diminished in the event of Brexit.
In his latest comments, Mr Wainwright claimed that having access to "maximum intelligence sharing arrangements" with European partners is "vital to the business of keeping our borders safe because you need that intelligence in order to know where to target your resources".
He added: "On something like people smuggling it's worth pointing out that here the Americans are not relevant, and neither are our intelligence agencies.
"It is, I think, a very good example of why we should continue to rely on EU cooperation mechanisms."