In this June 7, 2014, image from a security video provided by Philip Lao, San Marino Mayor Dennis Kneier tosses a bag of dog poo onto Lao's property. File picture: Philip Lao

San Marino, California - The doo-doo has become too deep for the mayor of a wealthy Los Angeles suburb who flung dog poop onto a political opponent's property.

The Pasadena Star-News reports San Marino Mayor Dennis Kneier resigned on Tuesday after an outcry from residents who say he smeared their image.

Kneier remains on the City Council. Councilman Eugene Sun will serve as mayor.

Kneier found the bag of dog waste on June 7 and tossed it on to the walkway of political opponent Philip Lao.

Lao recognised the mayor on surveillance video and called the police. Video of the incident went viral.

In his resignation letter, Kneier says his actions were inconsiderate and disrespectful and he's stepping down because the event continues to be embarrassing to him and to the city. - Sapa-AP