A Congressional Gold Medal has been awarded posthumously to four young black girls who lost their lives in the bombing of the 16th Street Baptist Church in Birmingham, Alabama.

Addie Mae Collins, Denise McNair, Carole Robertson, and Cynthia Wesley were preparing for Sunday school when the church was bombed on September 15, 1963.

Their deaths galvanised the civil rights movement and gave new impetus to the campaign that helped secure the enactment of both the Civil Rights Act of 1964 and the Voting Rights Act of 1965.

The medal was struck by the United States Mint and a ceremony held at the US Capitol Building on Tuesday.

"The 16th Street Baptist Church remains a powerful symbol of the movement for civil and human rights, and the ultimate sacrifices made by these girls are emblematic of many others who have lost their lives for the causes of freedom and equality," said a spokesperson for the United States Mint.

The medal's obverse was designed by United States Mint Artistic Infusion Program (AIP) Master Designer Barbara Fox and sculpted by United States Mint Sculptor-Engraver Jim Licaretz.

It features the silhouette of four young girls, representing the victims, with their names inscribed around the border of the design and the quote "Pivotal in the struggle for equality" inscribed across the front.

The medal's reverse features a view of the 16th Street Baptist Church designed by AIP Master Designer Donna Weaver and sculpted by Sculptor-Engraver Joseph Menna.