Ecuadorian police have prevented blocks of cocaine being loaded on to a Maersk boxship.

The port and airport investigation unit UIPA said in a statement that its officers and sniffer dogs from training centre CRAC had found 10 boxes of drug "bricks" in a container loaded with frozen shrimp at Guayaquil.

The 9.96 kg of contraband was about to be loaded on to the 9,640-teu Clifford Maersk (built 1999) last week.

The vessel was destined for Spain.

A dog named as King alerted agents to the presence of drugs on the container's cooling panels. A visual and manual inspection was then carried out.

The packages had been camouflaged for their voyage. An investigation has begun.

Ongoing problem

Drug trafficking remains a headache for the major container lines.

Maersk itself was the unwitting victim of a huge smuggling bid in the UK in September last year.

The UK's National Crime Agency recorded its largest-ever heroin bust, tracking nearly 1.3 tonnes of the drug — street value £120m ($164.2m) — from Felixstowe to Rotterdam on the 10,100-teu Maersk Gibraltar (built 2012).

The same month a routine check on an unnamed Maersk containership in Mexico uncovered 23 tonnes of the deadly painkiller fentanyl.

Mexican media said the drug was contained in 931 bags disguised as a cargo of calcium chloride, which is used in road salt.

The ship had arrived from China.

The painkiller is up to 50 times stronger than heroin and is responsible for a growing number of deaths worldwide.

US Customs and Border Patrol has said the drugs were probably headed to the US.