Bags of cannabis and suspected cocaine were seized after a drug deal was interrupted by police.
At around 4.50pm yesterday (Wednesday) near Pennington Bridge in Bootle, officers are said to have "sighted a drugs transaction".
A 27-year-old man from Bootle was arrested on suspicion of possession with intent to supply cocaine and cannabis.
During a search, officers found cannabis on his person.
A further search on Stanley Road recovered a "large amount" of cannabis and suspected cocaine.
The man has since been released under investigation.
The raid is the latest in Merseyside Police's Operation Pelican, an ongoing probe into crime in the Sefton area.
A Merseyside Police spokesperson posted on Sefton Police Facebook page yesterday evening: "Operation Pelican Officers have this afternoon arrested a male in the #Bootle area for Possession With Intent to Supply Class A and B Drugs.
"Officers have sighted a drugs transaction whereby a male was detained. During a search an amount of cannabis was recovered.
"Officers have then completed a search in the local area and recovered a large amount of cannabis and suspected cocaine."
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