At least four people have been injured after an old aircraft bomb exploded near a Munich train station.

German police said the device went off during construction work near Donnersbergerbrücke, in the east of the city on Wednesday. A column of smoke was seen rising from the site near the busy railway line.

"During tunnel work near the Donnersbergerbrücke, an aerial bomb exploded during drilling," Munich police said on Twitter.

"The danger area has been cordoned off, there is no danger outside this area," they added.

"Currently, more than 40 officers are on duty in the area ... and we also have support from two helicopters."

Train services through the nearby station have been suspended until further notice.

Unexploded bombs are still found frequently in Germany, even 76 years after the end of the war, and often during work on construction sites.

They are usually defused or disposed of in controlled explosions, a process that sometimes entails large-scale evacuations as a precaution.