The Prince of Wales has presented authorities in Montenegro with specialist equipment that will help tackle the illegal cigarette trade that costs the UK in lost duty and tax.
Charles met HM Revenue and Customs officials at the Villa Gorica residence of the Montenegrin prime minister Milo Djukanovic.
He was told how British crime experts are helping to tackle cigarette smuggling through Montenegro in a joint initiative between the two countries.
Speaking before meeting the Prince, HMRC assistant director Andrew Pavlinic said the memorandum of understanding, signed in 2014, had played an important role in keeping "Britain's crime borders as far from Britain as possible".
He added: "It is preventing crime before it hits our shores."
Mr Pavlinic explained that the illegal cigarette trade costs the UK some £2 billion a year in lost duty and tax - representing the largest loss to organised crime.
The National Crime Agency and HMRC provide training, advice and equipment to enable Montenegrin law enforcement to enhance their international co-operation.
It also helps them to tackle organised crime groups operating both in Montenegro and elsewhere on global smuggling routes.
Euan Stewart, head of intelligence at HMRC, said: "There is a significant movement of cigarettes which come through the Middle East and North Africa.
"This is especially significant in Montenegro," he said, explaining that this is largely due to the location of the country.
He added: "The organised crime threat is presenting real harms and the profit is being diverted to other crime and other things."
During the meeting, the Prince presented the Montenegrins with specialist customs equipment including binoculars, boots and special clothing.
After the event, Charles attended a young leadership reception hosted by the British Ambassador to Montenegro, Ian Whitting, where he met Only Fools and Horses star Nicholas Lyndhurst.
Earlier in the day, the actor attended an event with the Duchess of Cornwall to see how Unicef is piloting an app aimed at helping children stay safe from online sexual abuse.
Camilla also met children and their foster families as part of Unicef Montenegro's 'Every child needs a family' campaign.
The initiative aims to encourage more people to become foster parents to stop vulnerable children being placed in institutions.
Lyndhurst, a long term supporter of Unicef Montenegro, said: "It was really nice to welcome Her Royal Highness today to highlight the wonderful work that Unicef is doing promoting foster care in Montenegro.
"There's still a way to go but the foster carers I've spoken to so far are absolutely enchanted with what they're doing being a foster parent. I was lucky enough to be able to talk to the Duchess about that today."
He added there was still a stigma attached to fostering in Montenegro.
Lyndhurst added: "It doesn't really get much more high profile than the Duchess. I really hope her visit can help."