LONDON • British pop star Ed Sheeran has denounced anti-abortion activists for using one of his songs in their campaign days ahead of Ireland's referendum on abortion, The Guardian reported.

The song Small Bump, released in 2011 from Sheeran's debut album + was said to have been used by anti-abortion activists campaigning in Dublin's city centre.

Its lyrics includes lines such as "You're just a small bump unknown, you'll grow into your skin/With a smile like hers and a dimple beneath your chin/Finger nails the size of a half grain of rice, and eyelids closed to be soon opened wide/A small bump, in four months you'll open your eyes".

Sheeran took to his Instagram to distance himself from the activists, writing: "I've been informed that my song Small Bump is being used to promote the Pro-Life campaign, and I feel it's important to let you know I have not given approval for this use, and it does not reflect what the song is about."

Voters in Ireland will be asked on Friday whether to liberalise the country's abortion laws, a highly thorny issue in the traditionally devout Catholic country.

Abortions are only allowed in Ireland if the life of the mother is in danger.

An Irish Times/MRBI opinion poll on Thursday found Irish voters who favour liberalising abortion laws maintained a strong lead but the gap with those against change was narrowing, Reuters reported.