MADRID (Reuters) - The Basque militant group ETA will announce its final dissolution early next month, public television station ETB reported, just over a year since it ended its armed separatist campaign by surrendering guns and explosives.

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ETA killed more than 850 people during the campaign which lasted almost half a century and was aimed at creating a Basque state in northern Spain and southwest France.

The group declared a ceasefire in 2011 and handed over weapons caches in April 2017, bringing a close to Western Europe’s last major armed insurgency.

A Basque newspaper, Gara, had reported in February that ETA’s leaders would ask its members to vote on whether it should disband completely by the summer.

The group will announce its full dissolution during the first weekend of May, ETB reported. Details of the event are expected to be announced at a news conference on Monday by South African lawyer Brian Currin and other members of the International Contact Group mediating body, it said.

Spain’s Interior Minister Juan Ignacio Zoido said on Thursday that ETA has been defeated politically and operationally and has not achieved any of its goals.

“ETA has not achieved anything by stopping the killing and will get nothing for its dissolution announcement,” the minister said in the upper house of parliament.

ETA (Euskadi Ta Askatasuna - Basque Country and Freedom) was founded in 1959 and arose from anger and frustration among Basques, who have their own language and culture, from political repression under General Francisco Franco.

The campaign, which included political assassinations as well as bombings aimed at the general populace, escalated in the 1960s into violence that was reciprocated by the Franco dictatorship.

By the mid-1980s, years after Franco’s death, attacks including a 1987 car bomb at a Barcelona supermarket which killed a pregnant woman and two children, drew popular revulsion and international outrage.

The Basque campaign and the separatist movement has petered out partly due to a rejection of ETA’s violent tactics but has also lost support after the Basque region was granted a greater fiscal autonomy in 1981.

A current independence drive in Catalonia gained momentum after then regional leader Artur Mas asked Madrid to grant it a similar fiscal status as the Basque Country in 2012, a request roundly rejected by Prime Minister Mariano Rajoy.

The Basque fiscal autonomy, among the most generous of any region in Europe, dates back to the 19th century and is enshrined in Spain’s 1978 constitution.

If it were to be extended to Catalonia, an economically more powerful region accounting for a fifth of national output, the Spanish state would lose about 16 billion euros, according to a study by public research body CSIC.