MONDRAGON, Spain, March 10, 2008 (AFP) - Voters in Spain's Basque region heeded a call by separatists to boycott Sunday's general election despite an appeal from the daughter of a slain politician to cast ballots in her father's memory.

The abstention rate in the northern region of about 2.1 million was 35 percent in Sunday's poll, up from 25 percent in the last polls in 2004 and 10 percentage points higher than the national average, according to figures by the interior ministry.

The rise follows an appeal by the armed separatist group ETA for Basque voters to shun the polls in which Socialist Prime Minister Jose Luis Rodriguez Zapatero was re-elected, in protest against the 'oppression' by the Spanish state.

Batasuna, ETA's banned political wing, also called for voters to abstain as did two small Basque separatist parties, ANV and PCTV, which Spain's Supreme Court last month barred from taking part in the elections.

On the eve of the polls, the 19-year-old daughter of a former Socialists municipal legislator, Isaias Carrasco, who was shot and killed on Friday in the Basque town of Mondragon urged Spaniards to turn out and vote.

'Those who want to show solidarity with my father and our pain should turn out and vote on Sunday to tell the assailants that we are going to win,' Sandra Carrasco said in front of the town hall in Mondragon on Saturday.

There was no claim of responsibility for the attack but police said it bore the hallmarks of ETA which has killed over 800 people in bombings and shootings in its nearly 40-year campaign for an independent Basque homeland.

But even in the town of Mondragon, the abstention rate rose to 40.5 percent compared to 27 percent in 2004.

Separatists were quick to claim credit for the high abstention rate in the Basque region.

Marian Beitialarrangoitia, the ANV mayor of Hernani, a separatist stronghold Hernani, said it was 'the best proof of the abnormal character of these elections.'

'These were the most anti-democratic elections in recent times,' she said as she stood on top of a platform below a poster that read 'Abstentzioa' which means 'Abstention' in the Basque language.

The walls of the town were plastered in the runup to the election with purple posters depicting a voter throwing his ballot into the garbage with the slogan written in Basque: 'Abstention, independence for the Basque Country!'

Those who did vote though favoured the Socialists. The party captured 38 percent of the vote in the Basque region compared to 27.6 percent in 2004 when it was the second mosted voted party after the Basque Nationalist Party.

'This is the best result in our history,' said Patxi Lopez, head of the Basque Socialist Party.