"They are trying to take away rights that women attained in compliance with Islamic sharia," said Mervat Tallawy, head of the National Council for Women, adding that criticism of the council was an attempt to erode female rights.
The Muslim Brotherhood, whose Freedom and Justice Party (FJP) dominates parliament, has dismissed the council as an institution that was "a weapon of the former regime to break up and destroy families" in a statement on its website.
Association with ousted leader Mubarak and his first lady Suzanne, an outspoken but disputed advocate of their cause, has made it harder for women's rights campaigners to counter what they see as a threat from newly empowered Islamists.
Tallawy, named to head the council in February by the army-backed interim government, accused the FJP of smearing the council by depicting it as a tool of Mubarak's administration used to further foreign interests.
"They do not want a national institution for women," Tallawy told Reuters in an interview. "They have said that the international (women's) agreements are imperialistic and part of a foreign agenda."
The council was founded by presidential decree in 2000 and was overseen by Suzanne Mubarak until her husband's overthrow in a popular uprising in February 2011.
Its role is to propose public policies on women and implement international agreements that Egypt has joined such as the United Nations Convention on the Elimination of All Forms of Discrimination Against Women (CEDAW), which Egypt ratified in 1981.
Banned under Mubarak, the Brotherhood has emerged as a major force in Egyptian politics, its FJP party sweeping more than 40 percent of seats in parliament in election between November and January. The ultraconservative Salafi party came second.
The Brotherhood is now eyeing the presidency, with a June 16-17 run-off vote pitting its candidate Mohamed Mursi against Mubarak's last prime minister, Ahmed Shafik.
Mursi has pledged that, if elected, he would uphold women's rights including the ability to work and choose what they wear.
WOMEN'S POLITICAL REPRESENTATION
The FJP's written programme promises to "enable women to attain all their rights in so much as they do not contradict the basic values of society, and achieve a balance between their duties and rights."
Liberal Egyptians and many in the Christian minority fear the Brotherhood is hiding an intention to suppress individual freedoms and force its conservative brand of Islam upon society.
Tallawy said she was in a battle with Islamist MPs calling for the repeal of laws such as the "khulu", which allow a woman to divorce her husband if she returns money and belongings she received from him.
The MPs only backed down last month, she said, because of coordinated pressure from her council, the ministry of Justice and Al-Azhar, Egypt's highest authority on Sunni Islam.
Tallawy said she had also intervened against attempts by MPs to revise a law that allows women custody of their offspring until the children reach 15.
"There are many quarrels between me and parliament," she said.
FJP officials have said their party supports the khulu and custody laws.
But Tallawy says interpretations of Islamic text pushed forward by the FJP and other Islamist groups in Egypt derail women's progress. She accused the Brotherhood of failing to recognize treaties that Egypt has ratified on women's rights.
"My message to parliament: if you want a modern Egypt, you have to push for modern legislation that ensures empowerment of women, half of your human resources," she said.
She said she was battling for women to secure proper representation in a body that will write a new constitution.
The 100-member assembly selected by parliament earlier this year was dissolved by a court in April after lawyers and activists filed lawsuits saying it was dominated by Islamists and did not represent Egypt's diversity. Talks are under way to form a new constituent assembly.
"Women's rights must be set down in the constitution so they are not merely a gift bestowed by a president or parliament that is then taken back when they leave"," Tallawy said.
She said Egypt needed to reinstate a quota system, or amend its electoral laws, to ensure women were properly represented in parliament. Egypt previously had a quota of 12 percent of legislature seats but the law was repealed and women currently hold less than 3 percent.
"Our actual representation in the parliament does not reflect the true status of women in Egypt, their history, their struggle, their culture, their education," said Tallawy. "We have to push for our rights. We cannot keep silent."