Eleven people have been arrested during raids to tackle organised drug crime.
More than 160 police officers raided 10 sites in the Alway and Lliswerry areas of Newport from about 05:00 GMT followed by a further four.
They seized Class A drugs, several high performance cars, cash, jewellery and electrical equipment.
Eight men and three women have been arrested on suspicion of offences "relating to drug trafficking", Supt Ian Roberts said.
"This activity, doesn't just take place in isolation, it is just one aspect of a much larger fight to tackle serious and organised crime in Gwent.
"We have our eyes on these people and we won't stop this fight to dismantle these groups of criminals," he said.