Basque urban guerrillas kidnapped a rich industrialist and former official today, and the government - in an unprecedented move - complied with part of the kidnapers' demand.

The kidnaping of Javier de Ybarra, 63, in the industrial city Bilbao aggravated nationwide political tension less than a month from Span's first free legislative elections in 41 years. It capped eight days of violence in the Basque provinces and other parts of the county.

Relatives of the banker and former Bilbao mayor said the kidnapers disguised as hospital attendants, who spirted Ybarra away in an ambulance, said they wanted amnesty for Basque provinces and other parts of the country.

Relatives of the banker and fomer Bilbao mayor said the kidnapers disguised as hospital attendants, who spirted Ybarra away in an ambulance, said they wanted amnesty for Basque political prisoners.

The government announced late tonight that it would permit 23 Basque prisoners to leave the country if they petitioned to be exiled. The government statement did not mention the kidnaping, but observers here consider it a response to the guerrillas' demands.

The government had indicated earlier that it had 39 Basque political prisoners in custody, and no explanation was given for the discrepancy in figures.

The Spanish government has not complied with the demands of kidnapers in the past. Last winter it rejected demands for amnesty made by a leftist underground group that seized the country's fourth-ranking official and a general. Police eventually freed the two hostages.

The abductors were presumed to be members of ETA, the leftist Basque liberation movement, which had announced earlier this week that it would resume violent activities unless Basque prisoners - mostly ETA guerrillas - were freed.

The government has freed 78 Basquexpanded as part of the general move toward democracy.

ETA claimed responsibility for killing a policeman Wednesday night, apparently in retaliation for strong police repression of Basque amnesty demonstrations. Five demonstrators died, scores were injured and more than 150 were jailed.