Illegal immigration is one of the most serious threats facing Britain, the National Crime Agency (NCA) has warned in a report which revealed gangs are flying migrants into unguarded airfields.

In its annual assessment, the NCA said organised criminal gangs are taking advantage of the lack of security at many of the 950 ports, harbours, and marinas around 11,000 miles of UK coastline, and remote airfields with limited ability to monitor or stop the trafficking of migrants, drugs, and weapons.

“The UK has over 3,000 airstrips, presenting opportunities for criminals to use general aviation to exploit the UK border,” notes the agency, reporting its intelligence showed that organised crime groups (OCG) “have made significant investments in the purchase or hire of aircraft to facilitate illegal movement of people and commodities”.

“It is highly likely that OCGs will continue to use GA [General Aviation] in order to facilitate the illegal entry of migrants, in particular, into the UK,” the assessment adds.

An official said there were too few staff for the number of migrants https://t.co/kf1R2ezmUa — Breitbart London (@BreitbartLondon) February 20, 2017

However, the NCA found that refrigerated lorries remained the favoured method of transporting migrants, reporting that the agency recently disrupted a massive operation based in the north east of England which “was capable of providing an end-to-end service from Iraq to the UK, including travel within the EU and across the Channel”.

Using complicit truck drivers with hidden compartments built into their vehicles, the gang “would drop migrants off at pre-arranged times and places in the UK for collection”, with payments made via hawala — a traditional system of money transfer used in Arab countries and South Asia which is said to pose serious challenges to anti-fraud investigators.

In its report, which estimates there are 4,629 criminal gangs operating in Britain, the agency states “serious and organised crime affects more UK citizens, more often, than any other national security threat”, pointing to the 27 per cent rise in gun crime over the last year and the fact that “drugs deaths are at their highest level since comparable records began in 1993”.

NCA: Violent Albanian Gangs Have Control of UK Drug Trafficking Market https://t.co/xu0H90vWGE — Breitbart London (@BreitbartLondon) June 30, 2017

NCA Director General Lynne Owens said: “Criminals are continuing to develop international connections to increase the reach of their activity, and to maximise profits. We are also seeing ever-increasing crossover between crime threats, with finance at the heart of this.

“Organised criminals involved in smuggling of people or firearms also supply drugs, and the relationship between organised immigration crime and modern slavery is becoming more apparent.”

The report comes just days after it emerged that thousands of foreign gangsters monitored by the agency as linked to crime syndicates have been awarded British citizenship.

With the government having taken action on stripping citizenship from terrorists and sex offenders involved in grooming gangs, the news raised questions over Home Office oversight regarding high-level gangsters.