Some 1.1 metric tons of cocaine, worth $88m, is being tested in Kenya, amid fears that some of the drug may have leaked onto the international market.
Kenyan experts have been joined by a team of international monitors to find out if it has been tampered with.
Kenya's biggest ever haul of the drug is to be destroyed this week, following a court order last week.
It has been held since December 2004, while investigations were carried out to try and identify the traffickers.
Mystery
More than 900 sachets of the drug are being tested by Kenyan specialists, along with a team from the UN and forensic experts from the UK and the United States.
There has been widespread concern that some of the consignment might have found its way onto the international market after a number of Kenyan Airways staff were arrested in London with quantities of cocaine following the initial seizure.
The drugs have been kept under 24-hour guard at a military facility in the capital, Nairobi.
The verification process and subsequent destruction of the drugs - scheduled for the end of this week - has been shrouded in mystery.
Verification was to have begun on Monday but when the team arrived at the testing site, they were told the drugs had to be helicoptered in, checked and then flown out to another destination at the end of the day.
There have also been reports that some vital equipment needed for the exercise has gone missing.
^ Back to top | BBC Sport Home | BBC Homepage | Contact us | Help | ©