Four people have been charged with possessing 9kg of marijuana with intent to sell, Sofia City Prosecutor's Office and the National Police Directorate General (GDNP) said at a briefing.
Police arrested them in a special operation on 6 October as they were preparing a drug deal, GDNP deputy director Dimitar Antonov said. He said the investigation shows the group made such deals regularly.
They can be held for up to 72 hours. Nikolay Nikolaev, a spokesman for Sofia City Prosecutor's Office, said prosecutors will ask the court to keep them in custody. One of the four has a previous four-year prison sentence for a similar offence.
The investigation continues, and police are checking where the drugs came from.
Fentanyl is now sold through more scattered networks after the organised crime directorate (GDBOP) shut down a factory, said Kalin Rachev, head of the narcotics unit at GDNP. He said small groups are trying every way to get fentanyl and sell it, and the price changes with the quality.
Updated (08.10, 12:24): Police say the marijuana weighed nearly 10 kg, not 9 kg as first reported. They put its value at about €70,000. The operation took place in a car park of a large retail chain in Sofia. Two of those detained are brothers, aged 32 and 35, from the town of Elena. The other two, also aged 32 and 35, were guarding the drugs at another place in the capital. Chief commissioner Dimitar Andonov is deputy director of the General Directorate for Combating Organised Crime (GDNP).