The device, hidden in a milkman's can and planted near the outer wall of the ICRC facility in Peshawar, went off around 4:20 am (2320 GMT), senior police officer Shahid Khan said.

"The blast partially damaged the wall and shattered the windows of nearby houses but there were no casualties," Khan told AFP.

"It was not very powerful. It seems the motive was to create terror and harassment."

On Monday a bomb rigged to a motorcycle exploded outside a hotel in another part of Peshawar, injuring three people including a former senator.

In January a suicide bomber killed 14 people including two top police officers in Peshawar, which has a history of bomb blasts blamed on various groups including Islamic extremists.