A juror accused of contacting a defendant through social networking site Facebook is being prosecuted for contempt in a London court, in what is being seen as a British legal first.

A judge told Joanne Fraill she faces jail for exchanging messages on the site with the female defendant, Jamie Sewart, causing a multi-million pound drugs trial to collapse last year.

Taxpayers were left picking up a bill of 6 million pounds ($10 million) after the judge was forced to discharge the jury.

The case was heard by Lord Chief Justice Igor Judge -- the head of the judiciary, who earlier this year allowed the authorized use of short messaging service Twitter in the reporting of some court cases.

At the time, Lord Judge warned that courts must be satisfied that live text reporting does not interfere with the proper administration of justice.

The use of the Internet by jurors has already derailed several cases in countries such as the United States.

A Reuters Legal analysis conducted last year found that jurors' forays on the Internet had resulted in dozens of mistrials, appeals and overturned verdicts in the preceding two years alone. (http://www.reuters.com/article/2010/12/08/internet-jurors-idUSN0816547120101208)

The latest contact between juror and defendant occurred after Sewart had already been acquitted in the major drugs trial, but while the jury had still to reach verdicts on other defendants in the case.

Fraill is also accused of researching the defendants on the Internet, despite strict instructions by the judge to the contrary.

Fraill, 40, formally admitted contempt of court. The case against Sewart, 34 who was also in court, and who had denied contempt, was also found proved.

Sentencing is expected at a later date.

In a speech last year, Lord Judge warned that jurors could go to jail if they searched the Internet for information on defendants. The pair could each face up to two years in prison.

(Editing by Steve Addison)

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