A man who accidentally dropped a bag of cocaine on a Darwin casino betting table and then told police it was "just a few party drugs for tonight" has been convicted and fined.

In the Darwin Magistrates Court, Reza Passmore pleaded guilty to possessing 0.34 grams of cocaine while gambling at the Skycity Darwin casino earlier this month.

The court heard the small bag or "baggie" slipped out of his wallet while he was placing money on a betting table.

He then picked it up off the table, put it in his pocket and continued playing, the court heard.

In the meantime police came to the casino and viewed CCTV footage of the incident.

After watching the footage two officers went onto the betting floor and escorted Passmore to a holding room where he was searched and then arrested.

Officers asked Passmore about the baggie and he said it was "just a few party drugs for tonight".

When asked what sort of party drugs, he said "You know, just a bit of Charlie — cocaine", the court heard.

Passmore was fined $300.