Venezuelans have voted overwhelmingly in favour of claiming a disputed oil-rich territory long controlled by neighbouring Guyana.
More than 95% approved establishing a new state in Essequibo, officials say.
Caracas says the region has been part of Venezuela since independence from Spain 200 years ago, but Guyana says it was awarded to what was then British Guiana in the late 19th Century.
The dispute flared up again in 2015 after a major offshore oil discovery.
President Nicolás Maduro hailed the referendum result as an "overwhelming victory for 'Yes' throughout Venezuela".
Essequibo, an area of 159,500 sq km (61,600 sq miles), makes up two thirds of the land controlled by Guyana and is home to around a sixth of its population.
The status of the region has long been a source of tension between the two neighbours.
An 1899 ruling by an international arbitral tribunal awarded the territory to Britain, which at the time was the colonial power in Guyana, but in recent decades. successive Venezuelan governments have argued the ruling was unfair.
In 1966, the year Guyana gained independence, Britain and Venezuela agreed that a commission made up of representatives from Guyana and Venezuela would be set up to revisit the dispute, but six decades later no resolution has been reached.
The referendum follows the discovery in 2015 of oil in the waters off Essequibo's coast by US oil giant ExxonMobil.
In 2018, hoping to establish its claim on the territory, Guyana filed a case at the International Court of Justice (ICJ) that will establish whether the decision of the 1899 tribunal should stand. The ICJ is yet to deliver a ruling.
Venezuela has not accepted that the ICJ has jurisdiction over this issue, but has so far continued to attend the court's hearings.
Tensions increased further in September this year, when Guyana held an auction at which oil companies bid for exploration licences in Essequibo waters.
The referendum asked voters a series of questions, including whether they supported Venezuela's claim over Essequibo and whether they agreed with the government's refusal to accept ICJ jurisdiction.
They were also asked whether they agreed to "oppose by all means in accordance with the law" Guyana's "unilateral" use of the waters off the territory and if they supported Essequibo's "incorporation into the map of Venezuelan territory".
All questions were approved by more than 95% of voters, according to the president of the country's electoral authority.
Guyana has condemned the vote as an aggressive attempt at "annexation", while the ICJ ordered Venezuela on Friday to refrain from any concrete action that may alter the status quo in the Essequibo.
Critics have also condemned the poll as an attempt by Venezuelan President Nicolás Maduro to whip up nationalist fervour ahead of an election set to take place in 2024.
It is not yet clear what the Venezuelan government plans to do with the result of the referendum, but any attempt to take the territory by force would spark a strong international backlash.
Among the most significant could be the re-imposition of US sanctions on Venezuela's oil exports that only began to be eased in October.