The US military disputed the number of dead, saying only about seven people had been killed.
"A suspected suicide vest bomber attacked innocent civilians during a funeral in Mansuriyah [in Diyala province], northeast of Muqdadiyah, today at about 9.20am [06:20 GMT]," the US military told Al Jazeera.
"Initial reports indicate approximately seven local civilians were killed and 33 civilians were injured."
Iraqi Security Forces and Coalition forces have secured the area and US Army UH-60 Black Hawk helicopters provided medical airlift for the injured, the US military said.