Aid for Egypt should come with a warning that the country's women must not be excluded, Harriet Harman said, amid fears the revolution will see "the clock turned back".
Many women were involved in the mass protest movement that saw Hosni Mubarak's regime toppled in the most prominent success of the so-called Arab Spring uprisings.
But Labour's deputy leader returned from a visit to Cairo fearful that a decade of progress in women's rights there could ironically now be reversed.
And she has called on International Development Secretary Andrew Mitchell to ensure pressure is put on Egypt's leaders to ensure that does not happen.
Last month's G8 meeting promised extra financial help for Egypt and other countries emerging from popular uprisings - in part to support political and economic reform.
Ms Harman said it was vital to make clear it was being given on the basis of equal participation of women in both politics - such as the retention of parliamentary seat quotas - and business.
"The revolution is being used by those who always opposed women's rights as an opportunity to turn the clock back," she told Mr Mitchell in a letter.
"Though there are - from before the revolution - women in leading positions on constitutional issues, such as on the constitutional court, no women are included in any of the committees that are framing the new constitution.
"What happens in Egypt will send a strong signal - for good or ill - to the rest of North Africa and the Middle East.
"It is a pivotal moment and we must ensure that women in Egypt are able to play a full and equal role in their country's future in the way they demand - rather than seeing the clock turned back."