Its criminal law bans abortion in all circumstances, with a maximum punishment in theory of life in prison. While no one has been convicted, citizens and residents are forced to go to Spain or travel to Britain to have an abortion.

"I think we should be able to have an abortion here, we shouldn't have to go to a different country just to have an abortion," 20-year-old student Geraldine told Reuters after casting her vote.

"At the end of the day it is our body, our choice. Other people shouldn't make the choice for us," added the student, one of 23,000 Gibraltarians eligible to vote.

The referendum had originally been scheduled for March 2020, but was postponed because of the coronavirus pandemic.

Although penalties are tough, not a single woman or doctor has ever been convicted under the law, a Gibraltar government spokeswoman said.

The referendum is on an amendment to the criminal law that would allow pregnancies to be terminated by a registered physician within the first 12 weeks in cases where the pregnancy carried more risk to the mother's health than termination.

Abortions would be permitted at a later stage under a narrow set of circumstances.

Even if the changes are approved, the law would be far more restrictive than in most of the rest of Europe.

Pro-life groups say that the wording of the law could be interpreted in a way that would ultimately allow most abortions.

"I'm supporting 'No' because I believe life begins at conception and life is sacred and it should be respected until the moment of death," Susan Gomez, 52, who is a member of the Gibraltar pro-life movement, told Reuters.

"We should give (women who are pregnant) all the support in the world so that abortion never happens", she said.

Both the government, which has backed the proposed changes, and opposition parties in the enclave encouraged people to vote.

"The government will act in keeping with the views of the people of Gibraltar as expressed ... whichever of the two results may come out," Fabian Picardo, Gibraltar's chief minister, said.