Gay rights organisation Stonewall has branded the latest stunt from protesters Fathers 4 Justice as "obvious homophobia."
The group's original founder Matt O'Connor disbanded the group last week but disaffected "father's campaigners" staged a protest in Bristol today calling themselves "New Fathers 4 Justice."
The constituency office of junior health minister Dawn Primarolo was their target, and the banner they carried, "KIDS NEED REAL DADS NOT DAWN'S LESBO DADS," is the cause of the controversy.
Stonewall chief executive Ben Summerskill said:
"It is deeply sad that in trying to put across a point of view Fathers 4 Justice have descended into obvious homophiobia.
"Many thousands of lesbian couples bring up their childen together, something which sadly many members of Fathers 4 Justice do not."
Ms Primarolo, the MP for Bristol South since 1987, has been a vocal supporter of gay equality, including the Human Fertilisation and Embryology Bill.
Earlier this year Tory MPs tried to push through an amendment to the legislation that would have retained a requirement on doctors to consider the need for a father when assessing women for IVF treatment.
The government argued that the consideration has been used to disciminate against lesbians and single women, and they defeated the amendment.
The same breakaway Fathers 4 Justice group invaded the roof of Deputy Prime Minister Harriet Harman's house in June.
Mark Harris and Jolly Stanesby scaled Ms Harman's south London property, forcing her to leave several hours into their protest.
The pair claimed Ms Harman, who is also Leader of the House of Commons, had refused to meet with them.
Her office denied their claims.
Mr Harris and Mr Stanesby said they wanted to draw attention to the Human Fertilisation and Embryology Bill.
Fathers 4 Justice also claim that the courts discriminate against fathers.
There were ten protesters in Bristol today, dressed as superheroes, but Ms Primarolo had left the office 20 minutes before they arrived.
"Dawn has been a dogged and supportive champion of equality on this issue and it seems unfair she has been targeted in this way," said Mr Summerskill.
A local resident confronted them, according to 24dash.com.
The man, who did not want to be named, revealed that he had donated sperm to a lesbian couple.
"I came out to confront them because of what I saw as blatant homophobia," he said.
"I don't think they have intentionally come out to rile against homosexual rights or feminism but they are not doing themselves any favours.
"I believe strongly that people in a homosexual relationship should be able to have a family and I wanted to help that to become a reality for my two close friends who I have known for a long time.
"I felt that they would be really good parents with strong morals and that has nothing to do with their gender."
Mr Summerskill said that recent Stonewall research, funded and endorsed by the Home Office, showed that lesbian parents face abuse and intimidation.
It found that one in five gay, lesbian and bisexual people have been a victim of one or more homophobic hate crimes in the last three years and three in four don’t report the incidents to the police, many believing that no action will follow.
A mere one per cent of all victims said that a hate crime or incident resulted in a conviction.
"We know that lesbian parents frequently face homophobic incidents on the street, and this sort of abuse only encourages that," said Mr Summerskill.
Fathers 4 Justice protester Nigel Ace, 40, told 24dash.com:
"We have nothing against lesbians or gay people but we should not put them before fathers in our society and in my view they should not have children."