A homemade submarine capable of smuggling up to 2,000kg of drugs has been seized by police in Spain.

Investigators discovered the 9m (30ft) narco craft while it was being built in Malaga, on the Costa del Sol, during an international drug operation.

The light blue semi-submersible vessel, which is 3m (10ft) wide, is made of fibreglass and plywood panels and has three portholes on one side.

It has two 200hp engines operated from the inside.

Rafael Perez, head of the Spanish police, said the vessel had never put to sea.

He said: “We think that it has the capacity of about two metric tonnes but as it has never sailed we cannot prove this.

“What we think (is) it was going to go into the high seas, meet a mother ship, take aboard the stash… mainly of cocaine, we think.

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“And then of course return to port for the cargo’s transportation.”

Likening it to an iceberg, he added: “In practice, nearly all of it goes under water apart from the top, which is the only part of it that would be seen from another ship or a helicopter or from another location.”

He went on: “What we think happens is that the criminal organisation through the smuggling of hashish and marijuana is able to finance bigger operations, like for example cocaine.

“What we think is that this semi-submersible was going to fill up mainly with cocaine because they use a transport infrastructure to move hashish mainly by lorries.”

Similar drug-smuggling vessels have in the past been discovered in the Atlantic Ocean, especially off Central and South America.

They sit low in the water to escape detection and are rarely able to fully submerge.

The wider police operation targeting an international smuggling ring netted large quantities of cocaine, hashish and marijuana at a number of locations in Spain, and led to the arrest of 52 people.

Police in Colombia, the US, the UK, the Netherlands and Portugal were also were involved in the operation.