US lab probed over sports drug

Chambers tested positive for THG but denies knowingly cheating

A federal grand jury in San Francisco is to begin an investigation later on Thursday into the activities of a laboratory that is alleged to be the source of a banned performance enhancing drug called THG.

The grand jury will have to decide whether criminal charges should be brought against Balco Laboratories, a company supplying nutritional supplements to sportsmen.

Several well-known athletes and other sportsmen are among those called to give evidence over the next few weeks.

A number of leading athletes - including Britain's Dwain Chambers - have tested positive to THG.

But Mr Chambers says he has only received nutritional supplements from the lab, and has never knowingly cheated.

Unknown crime

Grand juries are used in the US to help decide whether or not to bring a criminal case and also in cases where publicity would be unfair if it is decided there is no case to answer.

Their activities are shrouded in mystery and this means the kind of charges prosecutors might be thinking of bringing against Balco are not known, says the BBC's Elizabeth Blunt.

And the hearings will be taking place behind closed doors.

Balco's president: Victor Conte

Balco's premises were raided in September in a joint raid by agents from the tax authorities, the Food and Drug Administration, an anti-doping agency and a narcotics task force.

Balco has a number of famous clients for its sport nutrition programmes, which involve testing athletes for deficiencies and treating them with supplements such as iron, zinc and magnesium - which is legal.

But the coach who tipped off the authorities about the existence of a new form of illegal steroid, modified to make it undetectable, named Balco as the source of the drug, which is why these grand jury hearings are attracting such attention, our correspondent says.

The founder and owner of Balco says he is not the source of the new drug, and denies that THG is an anabolic steroid.

His lawyers have said that he is the victim of "totally misguided and untrue" speculation, and that if he is brought to trial, they will prove him innocent of all possible charges.