Michel Fourniret has been detained since June 2003

Michel Fourniret, 62, told French investigators in Belgium that he had killed two more French teenagers, but denied a charge of killing an au pair.

Fourniret was arrested in Belgium last year on charges of kidnapping and sexual misconduct.

On Wednesday he confessed to raping and killing six girls over a 15-year period, Belgian officials say.

Four were French and two Belgian. They vanished between 1987 and 2001.

In his latest confession on Thursday, Fourniret said he had killed Celine Saison, 18, and Mananya Thumpong, 13, who went missing in France in 2000 and 2001.

Both of their bodies were found in Belgium.

Investigators were due to start digging in woodland at a chateau he once owned in the wooded Ardennes region on the Franco-Belgian border, where Fourniret said he had buried two of his victims.

Belgian prosecutor Anne Thily said Mr Fourniret admitted on Wednesday "six murders of girls" in Belgium and France between 1987 and 2001.

But she said up to a dozen people might have been killed.

Wife's claims

Fourniret is also reported to have confessed to killing a man in a robbery in a French highway rest area in the 1980s

The confessions by Mr Fourniret are said to have followed a decision by his wife to speak to police.

Monique Olivier, 55, has told investigators her husband could have committed up to nine murders.

She said the body of the couple's au pair, who went missing in 1993, was buried in southern Belgium.

Ms Olivier was arrested on Friday for failing to help a person in danger.

Following her interviews with police, Fourniret was charged with murdering the 16-year-old girl, whose name has not been released.

Officials say he may have escaped the eye of the authorities for so long because the crimes were committed on both sides of the border.

The victims included 12-year old Elisabeth Brichet, whom he confessed to raping and strangling in 1989.