Looks alike a Hollywood 50s movie. Definitely was black/white.
Plot: Some prisoners tried to escape by digging a cavity just using some food spoons. Finally, they did the job. Although they found a way to a sewerage manhole cover within a street but they didn’t escaped at that moment because they decided to return to prison for just one more night and wear some nice clothes or something like that before their escape which seems definitive.
Unfortunately at that night one of them reported them so they failed to escape.
“The Hole”, also known as “Le trou” (1960)
It is a French black and white prison escape movie from 1960, where the prisoners dig a tunnel, but they are betrayed.
Qoute from Wikipedia:
“Four long-sentence prison cell mates are determined to escape. Before they can start digging a tunnel,”
“However in the last moments, before the five are just about to leave through their tunnel, they understand that they have been betrayed.“
If you think that this is your movie, then please select my answer as Best Answer, there is an option for that.