Marshal taken to hospital in Houston over worries about syringe's contents as epidemic has spread to Nigeria

A US air marshal was attacked with a syringe at Lagos airport in Nigeria and has been taken to a US hospital, the FBI said on Monday.

It was not known what was in the syringe when its contents were injected into the on-duty marshal, whose name has not been given and is in hospital in Houston.

The incident on Sunday raised fears the syringe could have carried some form of the Ebola virus because Nigeria is one of the west African countries where the epidemic has spread.

The FBI said authorities were taking every precaution but that initial signs were that the victim was not a danger to others and was not showing any symptoms.

"Out of an abundance of caution, the Centers for Disease Control and Prevention conducted an on-scene screening of the victim when United Flight 143 landed in Houston early Monday morning," the statement said.

"The victim did not exhibit any signs of illness during the flight and was transported to a hospital upon landing for further testing. None of the testing conducted has indicated a danger to other passengers."