The armed Basque separatist group ETA has warned that the incoming government of the north-eastern Spanish region lacks "democratic legitimacy" and would therefore become the organisation's "priority target".
Basque militants declared a ceasefire in 2006, but resumed attacks 15 months later
The leader of the Basque Socialist Party, Patxi Lopez, is set to become the head of the regional Basque government under a deal reached with the conservative Popular Party following local elections in March.
Lopez, who will replace Juan Jose Ibarretxe of the moderately nationalist PNV party, will be the first Basque premier to unequivocally back the region's unity with Spain since it was granted wide autonomy in 1979.
Although the PNV won more seats than any other party in the polls, it failed to secure a majority in the 75-member regional legislature.
The Basque Socialist Party and the Popular Party combined have 38 seats -- enough to end almost 30 years of PNV dominance.
While the two parties do not plan to form a coalition, the conservatives have pledged to support Lopez as head of the regional government later this month or in early May.
ETA says Basque Socialist Patxi Lopez will become a legitimate target when he becomes premier
In a statement sent to the pro-independence Basque newspaper Gara, ETA said it "did not recognize any democratic legitimacy of the new government which will be formed."
"Just as we warned that Ibarretxe's government would be the government of fraud for any Basque nationalist, we now want to state that Lopez's government will be the government of fascism and the violation of rights," the statement said.
"As long as there is no change in behaviour, the political leaders of that imposed structure will be ETA's priority target," it added.
ETA has killed more than 800 people since the 1960s in its violent campaign for an independent Basque Country made up of parts of northern Spain and south-western France.
A lack of progress in peace talks with Madrid saw a 15-month truce fail in mid-2007. Since then, ETA has staged about 30 attacks and killed six people in Spain.