Ukrainian prosecutors have ordered a senior health official detained on suspicion of illegally importing millions of doses of a vaccine that they charge caused a teenager's death, officials said Wednesday.

United Nations agencies have concluded that the 17-year-old boy's death in May 2008 was caused by a bacterial infection unrelated to the U.N.-certified vaccine for measles and rubella he had just received.

But his death still led to widespread fears over immunization and caused health officials to terminate a campaign to revaccinate 9 million Ukrainians for measles and rubella.

Dr. Fedir Lapiy, an expert in infectious diseases based in Kiev, has said that the Ukrainian government, plagued by infighting between various political groups, has mismanaged the crisis. Lapiy says that some officials have used the investigation to discredit their political opponents instead of conducting a thorough probe.

Prosecutors have accused former Deputy Health Minister Mykola Prodanchuk of importing the vaccine without properly registering it here, which they say eventually led to the boy's death. They have provided no details on how the vaccine is alleged to have killed the boy.

Yuriy Boychenko, spokesman for the Prosecutor General's office, told The Associated Press Wednesday that a Kiev court issued a search warrant for Prodanchuk after he failed to show up for questioning. Prodanchuk must be detained while a court decides whether he should be held in custody pending the investigation, Boychenko said.

Prodanchuk, who resigned shortly after the teenager's death, has maintained his innocence. His lawyer, Mykola Shupenya, told the AP that he was in a hospital with an unspecified lung condition and could not appear in court.

UNICEF, the U.N. children's agency, declined to comment. The World Health Organization reiterated that officials believe the vaccine was not responsible for the boy's death.

Experts say termination of the vaccination campaign and the widespread refusals of vaccination could lead to major disease outbreaks in this France-sized country of 46 million and potentially spread to its European neighbors.