The 27-year-old won the prestigious London race in 2017 and was fifth in the 2018 New York Marathon.
"The AIU has provisionally suspended marathon specialist Daniel Kinyua Wanjiru of Kenya with immediate effect for an Athlete Biological Passport violation under the @worldathletics anti-doping rules," the AIU said on Twitter.
He was suspended for "use of a prohibited substance/method".
