Four men were arrested on suspicion of conspiracy of supply drugs as armed police carried out a planned drug operation.
Officers from Gwent Police carried out three warrants at addresses in Corporation Road and Stow Hill in Newport.
There was also a heavy police presence in Cefn Coed Road, Cardiff in the early hours of Wednesday 13 September.
Four men aged 36, 44, 60 and 66 were arrested on suspicion of conspiracy to supply drugs.
Detective Inspector Ian Bartholomew said: "We hope these warrants demonstrate our continued commitment to protecting our communities from the harmful effects of not only drugs but the criminality associated with them.
"The support of the public is vital to this work, I continue to urge people to let us know of any suspicious or unusual activity in their area so we can take action."
Corporation Road was closed in both directions at around 6am from B4237 Wharf Road to Eton Road as officers carried out the raids.
Some Newport Bus services were delayed as busses could not leave the depot.
The road reopened at 8.25am but six police vehicles remained on the road, as well as a few unmarked police vehicles and investigation team vehicles.
Officers used search dogs at two properties. All four men remain in police custody.
Police want those who are concerned about drug dealing in their area to call 101 or Crimestoppers anonymously on 0800 555 111.
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