The Women's Library, operated by London Metropolitan University, is widely regarded as one of Britain's leading specialist archives, attracting more than 30,000 visitors a year. London Met, however, said it was unable to fund the collection's £500,000-a-year running costs.
Last week, the institution's governors approved plans to transfer the archive to the LSE's social sciences library. Library staff will also move to the LSE, which will merge the collection with its own archives to create the Women's Library @ LSE.
However, the Save the Women's Library Campaign has vowed to fight the move, calling it "a step back for women's equality".
Campaigners are angry about the loss of the library's purpose-built home in Whitechapel, East London, which is only 10 years old. Designed by Clare Wright, the building was funded with a £4.2 million lottery grant and was named Best UK Building in 2002 by the Royal Institute of British Architects.
A campaign spokeswoman said: "Access is [about] more than opening times, and we find it hard to see how current plans will accommodate the vibrant exhibitions, education and events programmes that have opened up this collection to the wider public over the past decade."
Rushanara Ali, the Labour MP for Bethnal Green and Bow, said that losing the library would harm the East End's "vibrant intellectual and cultural life".
Wendy Davis, founder of Rooms of Our Own, a feminist pressure group, said the move had parallels with the Elgin Marbles dispute.
"Of course the British Museum looks after the Elgin Marbles very nicely, but that is not the point; they belong in Greece," she said. "Similarly the Women's Library collections belong in the purpose-designed Women's Library building."
However, Craig Calhoun, director of the LSE, said he believed the new library could "continue the excellent work that generations have put into building what is a fascinating record of a truly transformative women's movement".