Toxic package mailed to Blair

The package was addressed to Blair's residence at 10 Downing Street.

LONDON, England (CNN) -- Officials at Scotland Yard have issued an urgent warning that as many as 16 packages containing "toxic substances" have been mailed to government targets in Britain, including Prime Minister Tony Blair.

The parcels -- large brown envelopes -- consisted of a container of what appeared to be a complimentary sample of eucalyptus oil for aromatherapy and a leaflet explaining how to use the product, a Scotland Yard spokesman said.

Forensic testing determined the "oil" was sodium hydroxide, the spokesman said. Liquid sodium hydroxide can cause blindness, permanent scarring and even death. When it mixes with water, it can also generate enough heat to start a fire.

"The directions for use (in the package) are regarded by police to be cynically dangerous," said a statement from Scotland Yard.

Authorities were alerted to the parcels on Friday afternoon in a phone call from an anonymous man speaking in a Scottish accent and claiming to represent the Scottish National Liberation Army.

The man said 16 packages had been mailed, but only two have been identified -- the one sent to Blair and another sent to a Scottish legislator. Both were mailed last week, according to Independent Television News.

Blair was in Australia on Friday and the package, delivered to his residence at 10 Downing Street, was not opened. Normal screening procedures alerted authorities to that package.

The Scottish National Liberation Army was formed in the 1980s and has a history of bombings and sending letter bombs. More recently, the group moved toward a strategy of "disruption," in which they make bomb threats that turn out to be hoaxes.

Scotland Yard said this incident is in no way linked to the September 11 terrorist attacks in the United States, but is connected to domestic political issues. Authorities warned politicians in England and Scotland, and members of their staff, to be wary of suspicious parcels.

In 1995, a part of the SNLA broke away and became a legitimate political organisation called the Scottish Separatist Group. Its aims are to halt and reverse English immigration into Scotland, to restore Gaelic as the national language of Scotland, and to establish and maintain an independent Scottish republic.