The number of drug smugglers intercepted at Schiphol airport fell by around a fifth in 2015 after more stringent checks were introduced on known trafficking routes, NOS reports.

In total 645 smugglers were detected on flights arriving from Surinam, the Dutch Caribbean islands and Venezuela, compared to 822 in 2014. The number has been falling since the last peak of 880 in 2012.

A spokesman for the Dutch customs service said it was too early to say if measures introduced to deter drug traffickers from going through Schiphol were working. ‘Our experience in general is that organised crime responds to government measures. If certain routes become too risky or the chance of being detected and intercepted is too high, they’ll look for alternatives.’

In 2003 customs officers started checking every passenger on flights from Curaçao, Aruba, Sint Maarten, Bonaire, Suriname en Venezuela. The move followed a spate of so-called bolletjesslikkers – drugs mules who swallow bagfuls of illegal narcotics to smuggle them through airports.

More recently customs officials have refined the policy using passenger lists to identify likely drug mules through tell-tale signs such as tickets being paid in cash or at short notice.