SPANISH PRIME MINISTER JOSE LUIS RODRIGUEZ ZAPATERO ANNOUNCED A SURPRISE CABINET SHAKE-UP ON FRIDAY, NAMING A SOCIALIST HEAVYWEIGHT TO THE CABINET AS THE GOVERNMENT COMES UNDER INCREASING FIRE FROM THE OPPOSITION, REUTERS REPORTED. ALFREDO PEREZ RUBALCABA, ONE OF THE PARTY'S MOST AGILE POLITICAL NEGOTIATORS, WILL TAKE OVER AS INTERIOR MINISTER, ONE OF THE MOST PROMINENT POSTS IN A GOVERNMENT THAT HAS FOCUSED ALMOST ENTIRELY ON DOMESTIC ISSUES. RUBALCABA WILL HAVE A KEY ROLE IN ANY ADVANCES AFTER A CEASEFIRE ANNOUNCED BY ARMED BASQUE SEPARATISTS ETA. FORMER INTERIOR MINISTER JOSE ANTONIO ALONSO MOVES TO THE DEFENCE MINISTRY TO REPLACE JOSE BONO, WHO HAS COME UNDER REPEATED FIRE FOR A SERIES OF GAFFES. RUBALCABA WAS THE FACE OF FELIPE GONZALEZ'S SOCIALIST GOVERNMENT IN ITS TOUGHEST PERIOD IN THE EARLY 1990S. UNDER ZAPATERO, HE HAS BEEN THE PARTY'S OFFICIAL SPOKESMAN IN PARLIAMENT. 'JOSE BONO HAS LONG TOLD ME THAT HE WANTED TO BE RELIEVED FROM HIS POST AND WE DECIDED THAT THIS WOULD BE THE MOMENT AS CERTAIN LEGISLATION HAS BEEN FINISHED,' ZAPATERO TOLD A NEWS CONFERENCE CALLED AT THE LAST MINUTE. THERE HAD BEEN TALK OF A CLASH BETWEEN BONO, A STRAIGHT-TALKING POPULIST, AND FOREIGN MINISTER MIGUEL ANGEL MORATINOS, A RESPECTED, SOFTLY SPOKEN DIPLOMAT. THE OTHER CABINET POST TO CHANGE WAS THE EDUCATION PORTFOLIO, WHICH WILL BE TAKEN BY MERCEDES CABRERA, A PROFESSOR AT ONE OF MADRID'S UNIVERSITIES.