Two 16-year-old students from London arrested in Ghana 10 days ago allegedly carrying £300,000 of cocaine have been "provisionally charged".
Drug prevention posters are outside the airport in Accra
Yasemin Vatansever and Yatunde Diya were stopped as they tried to board a plane at Accra airport on 2 July.
The investigating team said the girls had told family they were going on a school trip to France. Instead, they went to Ghana for six days.
If found guilty it is thought they could face at least 10 years in jail.
The Foreign Office said the pair had appeared in court charged with possessing and attempting to export an illegal substance.
Ghanaian Narcotic Control Board officers working as part of Operation Westbridge with HM Revenue and Customs (HMRC) were said to have found the drugs in laptop bags carried by the girls.
Two Ghanaian men apparently paid for their accommodation in Accra. The girls have told police the men gave them the laptop bags.
Fair Trials Abroad (FTA) said one of the girls' family had contacted them and they were looking into the case.
Sabine Zanker, of FTA, said cases such as these were usually dealt with fairly quickly in Ghana, which has a good legal system.
She said: "The higher the court, the better it gets - there is corruption in the lower courts and police ranks but the government is very determined to fight against corruption".
She added that the Ghanaian government was working with the UK on drugs cases.
Operation Westbridge is designed to stop traffickers getting drugs into the UK and Europe through the West African country.
British and Ghanaian customs officials have intercepted more than 200kg of cocaine between Accra and British airports since November.
Interpol estimates more than a third of the cocaine arriving in Europe is trafficked through West Africa.