The new constitution being debated this weekend by Cuban legislators would provide a legal path for same-sex marriage, an important demand of the socialist island's LGBT community.

The document's Article 68 would define marriage as the "voluntary and consensual union between two people" without specifying their biological sex, the official newspaper Granma said Saturday, reporting on National Assembly debates over the proposed changes in Cuba's basic law.

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The current constitution, dating from 1976, limits marriage to the "voluntary union of a man and a woman."

The change would "open the door to legalising homosexual couples for all posterity," Francisco Rodriguez, a journalist and well-known gay activist who is also a member of the governing Communist Party, wrote in his blog.

By incorporating "the principle of non-discrimination based on sexual orientation and gender identity," the new wording could facilitate other legal and policy changes to protect the island's LGBT community, he said.

Still, Rodriguez warned that "the fight ahead will not be easy." Certain political and ideological forces will "do everything possible to wreck these dreams," he said.

For more than a decade, the lawmaker Mariela Castro, daughter of former president Raul Castro, has promoted LGBT rights.

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In the early days of the 1959 revolution, gays were persecuted in Cuba, even sent to forced labor "re-education" camps.

Mariela Castro, as director of the Cuban National Center for Sex Education, has long advocated for same-sex marriages.

"Giving rights to those who lack them does not imply taking them from those who already have them," she said in a parliamentary debate broadcast on local television on Friday.

But another lawmaker, while applauding the move to same-sex marriage rights, expressed concerns about gay couples adopting children.

The proposed changes do not specifically address that issue.

The National Assembly is to vote on the new constitution, prepared by a parliamentary commission under Raul Castro and President Miguel Diaz-Canel, between now and Monday. It will then be submitted to a popular referendum for final approval.

The document has also drawn attention for recognising the free market and private property, while encouraging foreign investment.