"Around 100 tonnes of powder, 2.6 million detonators, 99 projectiles and around 3,000 cannon shells were found," said Luis Gonzalez, national director of the attorney general's office.

Photographs from the prosecutor's office showed cases inside a shipping container with labels stating Chinese defence manufacturer Norinco as the supplier.

The recipient was stated as importer Tecnoimport in the Cuban capital Havana. Neither company could be reached for comment.

Beijing's foreign ministry spokeswoman Hua Chunying maintained that the ship was operating within Chinese and international law.

"The vessel is carrying ordinary military supplies and utilities to Cuba; there is no sensitive substance on board," she said.

The ship's captain, Wu Hong, will be brought before a judge in order to be detained pending charges, and has been provided with an interpreter. Officials said he could be charged with illegal transport of military materials.

No further information about the ship or its crew was released.

A North Korean ship was detained in the Caribbean region in July 2013, near the Panama canal, when it was found to be carrying Soviet-era weapons from Cuba including two MiG-21 jet fighters, hidden under thousands of tonnes of sugar.

The United States and the UN both blacklisted two shipping companies which they said tried to hide the arms shipments destined for North Korea.

Panama freed the ship and 32 crew to sail to Cuba a year ago - but it was later sighted in China after its registered name was changed, UN documents reveal.