South Korea has joined Mexico and Lebanon as countries that have yet to destroy all samples of the killer influenza virus (search) they received as part of routine test kits, the U.N. health agency said Tuesday.

But all three countries have made progress in tracing the missing shipments from the United States and the total destruction of the samples is possible, said Klaus Stohr, influenza chief of the World Health Organization (search).

U.S. laboratories, which received the vast majority of the samples, have destroyed more than 98 percent of them, Stohr said.

Stohr said that the shipper of the sample that went astray in Lebanon had turned it over to another shipper for local delivery, but it never arrived at the intended laboratory and work is under way to locate the kit with the delivery service so that it can be destroyed.

The missing shipment to Mexico has been tracked down in a bonded warehouse, and "a team is now on its way" there to destroy it, he added.

Three South Korean laboratories said they had never received shipments made last year, but the shipper has signatures indicating that the packages had been delivered and an attempt is being made to determined what happened to them, Stohr said.