The Real Madrid defender is now likely to miss his club's end-of-season run, meaning his participation in this summer's World Cup is also in doubt.
The 31-year-old right back had initially hoped to be missing for three to four weeks with the problem, but has confirmed the news is worse than expected.
Arbeloa last played in the 2-2 derby draw against Atletico Madrid on March 3 and was left out of the Spain squad to face Italy the following week.
Following a medical review of his injury Thursday, Arbeloa told Goal: "I will be out for a minimum of eight weeks. In the end, the injury has proven to be much more serious than it first looked."
The injury comes at the worst possible time for the veteran, who is fighting for his future at the club and international level.
Arbeloa has started just 13 La Liga matches this season as he comes under pressure from Dani Carvajal, while Chelsea's Cesar Azpilicueta and Atletico defender Juanfran are his selection rivals for Spain.
Madrid's league season ends in nine weeks when it plays Espanyol at the Bernabeu on May 17, giving Arbeloa virtually no chance to build up form and fitness in time to play a meaningful part of what could be a decisive fixture.
Spain has a World Cup warm-up match against Bolivia on May 29 that may be a more realistic fitness target, but his participation will depend on whether coach Vicente del Bosque is prepared to select him coming off an injury.