Banksy Graffiti

Secretive British graffiti artist Banksy bought this painting for $50, added a Nazi officer, and gave it to a charity to sell. (Housing Works/The Associated Press)

Bidding on a painting that British graffiti artist Banksy bought for $50 and altered has climbed to more than $310,000.

Banksy added a Nazi soldier into the pastoral scene after he purchased the painting at a Manhattan thrift shop. He donated it back to the 23rd Street Housing Works store in New York city on Tuesday.

The store put it up for auction the same day.

The auction ends Thursday at 8 p.m.

Proceeds will benefit Housing Works' homelessness and AIDS initiatives.

As he does with all his works, the elusive artist posted the image on his website. He titled it, "The banality of the banality of evil."

Known for his often-funny, but always thought-provoking, guerilla street art, the Britain-based Banksy is currently doing a residency in New York.

On Sunday, Banksy posted an essay on his website calling the design of 1 World Trade Center, the skyscraper being built at ground zero, a "disaster."