CARACAS, Venezuela (AP) — Venezuelans on Sunday approved a referendum called by the government of President Nicolás Maduro to claim sovereignty over an oil- and mineral-rich piece of neighboring Guyana, the country’s electoral authority announced.

Few voters could be seen at voting centers throughout the voting period, but the National Electoral Council claimed more than 10.5 million voters cast ballots.

Venezuela has long argued the territory was stolen when the border was drawn more than a century ago. But Guyana considers the referendum a step toward annexation, and the vote has its residents on edge.

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Venezuelan voters were asked whether they support establishing a state in the disputed territory, known as Essequibo, granting citizenship to current and future area residents and rejecting the jurisdiction of the United Nations’ top court in settling the disagreement between the South American countries.

Throughout Sunday, long lines typical of electoral events did not form outside voting centers in Caracas. Still, before the 12-hour voting session was scheduled to end, the country’s top electoral authority, Elvis Amoroso, announced polls would remain open for two additional hours, and he claimed, without giving numbers, “massive participation” in the referendum.

The practical and legal implications of the referendum remain unclear.