A well-known figure in Stamford Hill's Charedi community has urged Jews to avoid the optional question on religion in the Census because it contravenes Jewish law.
JJ Rosner, who runs a number of medical charities, took issue with advice from other strictly Orthodox organisations for community members to respond to the religion question.
This guidance was "not in conformity with the Torah law which prohibits counting the Jewish population", he argued in a Charedi newsletter.
The Bible records that King David brought a plague on his kingdom for conducting a census without divine permission.
"Unfortunately, members of our community have lately been stricken with unprecedented tragic fatal events," Mr Rosner wrote. "Do not contravene the Torah and do not sacrifice your life and your family's life for the benefit of a few fundraising organisations."
The last Census a decade ago produced a significant undercount of Jews in Hackney as large numbers from the Orthodox community opted not to answer the voluntary religion question.
This time Charedi charities have encouraged residents to answer it because they believe it is necessary to have an accurate figure for the Jewish population in order to get funding for social services, housing and other needs.
A source close to the strictly Orthodox rabbinate said that although Mr Rosner was entitled to his opinion, the rabbinate did not share it. "The rabbinate has got nothing against it," the source said. "If they had, they would have come out and said so."
The prohibition applied only to a direct head count of Jews, he explained, whereas the Census count was not being conducted by Jews. "It is a form processed by computer for all the population in the country. It doesn't come under the prohibition against counting."
A guide in Yiddish to filling out the form has been produced by the Census authorities to encourage a greater response from the strictly Orthodox.
But Charedi representatives believe the gesture was unnecessary - and in any case, Hebrew would have been a more useful language to help those who have come from Israel.