Image copyright Reuters/Getty Image caption Oprah Winfrey (l), Chadwick Boseman (c), Lena Dunham (r) are among the stars who signed the open letter

Scores of celebrities are calling on world leaders to take urgent action against global gender inequality.

Oprah Winfrey and Meryl Streep are among the big names putting political leaders "on notice" in an open letter led by international charity ONE.

The 140 signatories demand a commitment to help every girl get an education and for leaders to use their power to deliver "historic changes for women".

Black Panther stars Letitia Wright and Chadwick Boseman have also signed.

Actors from the UK - including Michael Sheen, Thandie Newton and Natalie Dormer and the US - including Lena Dunham, Natalie Portman and Issa Rae - took part in the charity's global call to action.

In the wake of recent movements against sexual harassment, Nashville star Connie Britton said in a statement: "We have seen an astounding level of attention paid to the harmful impacts that sexism and systemic gender inequality have on our society."

The Emmy-nominated actress, who endorsed the letter, went on to say, "This year, it is my hope that all of us, especially our leaders, join in the fight for full equality."

The letter describes poverty as sexist and said: "We won't stand by while the poorest women are overlooked."

Media playback is unsupported on your device Media caption The Afghan girls returning to school

The equality gap between men and women would take 100 years to close at its current rate, the World Economic Forum reported last year.

Campaigners hope many other people will sign the open letter.

It has also been endorsed by prominent names outside of the entertainment industry including former US Secretary of State Madeleine Albright, Facebook's Sheryl Sandberg, Huffington Post founder Arianna Huffington, Ngozi Okonjo-Iweala, a former Nigerian minister and Mozambican politician Graça Machel.

The letter reads:

"Dear World leaders,

We're putting you on notice.

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.

There is nowhere on earth where women have the same opportunities as men, but the gender gap is wider for women living in poverty.

Poverty is sexist. And we won't stand by while the poorest women are overlooked.

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."