A passenger was caught with nearly 20,000 illegal sexual enhancement pills in her suitcase in Spain.

The woman, 63, was apprehended at Alicante-Elche Airport on January 18 for attempting to smuggle the pills, suspected to be contraband and a public health violation.

The discovery was made during a security inspection of luggage from a flight originating in Madrid and transiting through other countries.

X-ray scans revealed unusually dense contents in a bag, which, upon inspection, was found to contain blue pills labelled 'sildenafil citrate,' a drug used to treat erectile dysfunction.

Customs officials said the woman was unable to provide documentation to justify the possession or transport of the drugs.

The Guardia Civil and the Spanish Tax Agency seized the pills for further investigation.

Authorities are analysing the substances to determine if they are altered or counterfeit, with further testing to be conducted by the Pharmaceutical Inspection Services in Alicante.

The suspect was released with precautionary measures while legal proceedings are ongoing.