Sixty-seven live giant African snails have been seized by US custom officials at Los Angeles International Airport.

The 2lb snails, which measured 15cm in length, arrived from Lagos, Nigeria, marked for an address in San Dimas, California, about 30 miles (48km) east of Los Angeles.

It was the largest shipment ever to be seized at the airport, the US Customs and Border Protection agency said.

Investigations are underway to find out the motive behind the shipment but officials have ruled out smuggling.

The creatures, considered a delicacy in Nigeria, are prohibited imports because they pose a serious threat to the environment, agriculture, and to public health. The snails carry parasites harmful to humans including one which leads to meningitis.

They are among the largest land snails in the world and can grow up to 20cm in length.

The entire snail collection was incinerated by the US Department of Agriculture after they were inspected.

Maveeda Mirza, the Custom and Border Protection programme manager for agriculture, said: "We're investigating what happened, but it doesn't seem like there was smuggling involved."