Updated

Authorities have seized the tusks of 58 elephants — totaling one ton of ivory — after sniffer dogs led investigators to containers at the country's main airport that were bound for Nigeria, officials said Friday.

Joseph Ngisa, the officer in charge of criminal investigation in the country's airports, said no arrests had been made. It was not immediately clear why the ivory was being transported to the West African nation; the most common destination for smuggled ivory is Asia.

"We are suspecting they could be from here or neighboring countries and we are on their toes. We must get them. They have killed many, many elephants and we cannot allow this," said Eunice Kiheko, the deputy police chief in charge of all airports.

Patrick Omondi, an expert on elephants at the Kenya Wildlife Service, says illegal ivory smuggling in Africa increased after the 2007 temporary lifting of a ban by the Convention on International Trade in Endangered Species. It allowed a one-off sale by countries that had stockpiles of ivory from elephants that had died naturally or problem elephants killed by wildlife officials.

In 2007, Kenya lost only 47 elephants to poaching, Omondi said. In 2008 — the year the sale took place — Kenya lost 145 elephants. In 2009, 271 elephants were killed and 187 were killed in 2010. Omondi said Kenya has already lost 87 elephants this year.

In a separate incident on Friday, a Vietnamese customs official said 661 pounds (300 kilograms) of smuggled African elephant tusks had been intercepted at a northern port city.

Vu Hoang Duong, head of the customs division at Hai Phong's port, said the tusks from Tanzania were discovered in a container that had been declared as a rubber shipment. The tusks were sealed in iron boxes and hidden beneath scrap metal.

The shipment arrived in April, but Duong said officials discovered the tusks on Thursday. It was addressed to a company in northern Quang Ninh province. The company denied knowing the tusks were included in the shipment.

Vietnam is a common destination for illegal animal products, including African elephant tusks and rhino horns, which fetch large amounts for their perceived medicinal benefits. Last month, Thailand confiscated two tons of ivory valued at $3.3 million that had been shipped from Kenya.

(This version CORRECTS Corrects title of Eunice Kiheko to deputy police chief in charge of all airports.)