According to Rene Gottschalk, head of the German city’s local health authority, another 150 people are being assessed after they had contact with those who have tested positive.
The service at the Evangelical Christian Baptist Church was attended by 180 people, Gottschalk said.
It took place two weeks ago.
Many of the infections occurred after worshippers left the service.
The Frankfurt church community initially insisted that all hygiene and distancing measures currently in place to curb the pandemic were adhered to, but a statement posted on its website on Monday admitted to shortcomings.
“In retrospect, it would be appropriate for us to wear protective mouth-and-nose covers during the service and to refrain from singing together,” it said.
Places of worship have gradually reopened in Germany over the past month, along with various other areas of public life, due to gains made in reducing the rate of infection. (dpa/NAN)