(CNN)Oprah Winfrey, Madeleine Albright and Reese Witherspoon are among 140 activists, actors, business leaders and philanthropists to sign an open letter to world leaders demanding that they take action to close the gender gap and combat poverty.
Celebrity influencers to world leaders: 'We put you on notice'
"We're putting you on notice," the letter reads. "For 130 million girls without an education. For one billion women without access to a bank account. For 39,000 girls who became child brides today. For women everywhere paid less than a man for the same work."
The letter is part of the "Poverty is Sexist" campaign spearheaded by ONE, an advocacy group co-founded by U2 singer Bono.
"There is nowhere on earth where women have the same opportunities as men, but the gender gap is wider for women living in poverty," the letter says.
Valerie Amos, Chelsea Clinton, Arianna Huffington and Sheryl Sandberg are among the scores of influential signatories on the letter, ONE says.
The convener of Nigeria's "Bring Back Our Girls" campaign, Oby Ezekwesili, also signed, as did actors and comedians including Meryl Streep, Tina Fey, Amy Schumer and Juliette Binoche.
CNN anchor Isha Sesay and quarterback Tom Brady also put their names to the campaign.
ONE, which describes itself as "a campaigning and advocacy organization of more than nine million people around the world taking action to end extreme poverty and preventable disease, particularly in Africa," marked International Women's Day March 8 by urging people around the world to sign the letter.
"Poverty is sexist. And we won't stand by while the poorest women are overlooked," the letter to leaders reads. "You have the power to deliver historic changes for women this year. From the G7 to the G20; from the African Union to your annual budgets; we will push you for commitments and hold you to account for them. And, if you deliver, we will be the first to champion your progress.
"We won't stop until there is justice for women and girls everywhere. Because none of us are equal until all of us are equal."
ONE President Gayle Smith said support for the letter indicated that "2018 could not be business as usual."
"Until we're able to break down the barriers holding girls and women back on a global level, extreme poverty and gender inequality will continue to exist," she said in a statement.
A separate letter calls specifically on Canada's Prime Minister Justin Trudeau -- who replied to ONE's 2016 International Women's Day letter to world leaders, agreeing that "poverty is sexist."
Canada is hosting the G7 Leaders Summit June 8-9. Trudeau announced in December that advancing gender equality and women's empowerment would be key themes of his nation's presidency of the group.
ONE is urging Trudeau to back "a big idea that could kick-start momentous change: a bold new initiative that brings governments and the private sector together to fund programs and change policies designed to empower women in the poorest countries."
The group said it had been encouraged by the Prime Minister's words of solidarity, "now we want to see action," it said.
"Dear Prime Minister Trudeau, Please invest in girls and women in the world's poorest countries to unlock their full potential. Commit to a bold initiative at the G7 summit that enables at least 100 million women to learn, work and increase their independence," the letter reads.
The G7 consists of the industrialized nations of Canada, France, Germany, Italy, Japan, the United Kingdom, and the United States.
Correction: A previous version of this article misspelled the names of Madeleine Albright, Amy Schumer and Juliette Binoche.