The two images were posted to Banksy's Web site Monday -- one depicts an Olympic javelin thrower holding a missile, while another shows a pole-vaulter jumping over a barb-wire fence onto an old mattress.
The locations of both pieces were not identified.
Banksy's images appeared soon after several arrests of London graffiti artists last week, "part of a preemptive sweep" before the Olympics, The Guardian reported. The four men were then released under bail conditions that prohibit them from owning spray paint or being "within one mile of any Olympic venue in London or elsewhere in England."
According to the New Statesman, British Transport Police said the Olympic-venue condition "was to prevent the commission of offences and to protect the integrity of the Olympic Games."
One graffiti blog, however, accused British police of "sanitizing" the city before the Games.
"The heavy handed actions of government and law enforcement in London could see our fair capital descend into the cultural deadzone," The London Vandal argued.
The Guardian's Jonathan Jones agreed, calling official attitude toward graffiti "a chilling sign that instead of magnifying or rekindling the reputation London now has for outrageous art and irrepressible creativity, this corporate behemoth is cancelling out the capital's attractions and drawing attention to its weaknesses."
Helen Bingham of anti-litter organization Keep Britain Tidy noted that not all graffiti is created equal.
"There's a difference between low grade tagging and the work people like Banksy do," Bingham told the BBC. "You have to look at it and know the difference - it's not a black and white thing."
Street art has long served as important fixture on London's urban landscape--murals and graffiti color the walls of neighborhoods like Camden and Shoreditch.