The snakes were discovered by agents at Goumois, at the French border, when they checked a vehicle registered in France last week, the Swiss federal customs administration said on Tuesday.

Their attention was drawn by a polystrene box in the back of the car.

When they opened it, the customs officials discovered the snakes coiled inside.

The royal python is a listed species under the Convention on International Trade in Endangered Species (CITES).

The reptiles being brought from France were destined for illegal sale in Switzerland, customs officials said.

The pythons were seized and placed in a vivarium in Switzerland, customs said.

An investigation was opened into the case by the customs anti-fraud department in Basel.

It turns out there have been other similar seizures of the species by Swiss customs officials.

Last September, officials in Stein in the canton of Aargau caught a German man attempting to smuggle a royal python across the border in a van, along with four other snakes, including two boa constrictors, and four geckos.

The man was fined 1,200 francs after he was unable to provide the necessary documents proving ownership of the reptiles.

The royal python, a non-venomous snake that commonly grows to a length of about 120 centimetres, is native to an area of Africa stretching from Senegal to the Democratic Republic of the Congo.

Experts believe it got its name from reports that Cleopatra, the Egyptian pharaoh, wore the colourful snakes as bracelets around her wrists.

Although the python is not currently considered to be endangered, it was listed under an appendix to CITES in a bid to regulate trade in the species.