The Equality and Human Rights Commission has said it will continue to lobby for the next census to include a question on sexual orientation.

In its business plan for 2009/2010, published on Friday, it stated one priority as: “Continue to lobby for a question on sexual orientation to be included in the 2011 census.”

Critics have said the question, which would ask whether people see themselves as heterosexual, gay, lesbian or bisexual, is overly intrusive and highly personal.

The Office for National Statistics decided several years ago that it would not include the question, saying it was “not suitable”.

After a consultation was held in March 2006, it said: “ONS has significant concerns surrounding the issues of privacy, acceptability, accuracy, conceptual definitions and the effect that such a question could have on the overall response to the census.”

Although supporters of the gay question say it is necessary to provide appropriate services to lesbian, gay and bisexual people, it is thought that many people will refuse to answer or not answer the question truthfully due to family pressures or embarrassment.

Instead, the ONS has said it will include a sexual orientation question in its Integrated Household Survey, which will be published in 2010.

Every household is legally required to fill out a census form once every ten years. The 2011 census will ask for the first time whether respondents are in a civil partnership.