BlackRock, the world's biggest money manager, has dipped its toes into Spain's battered government debt market in recent weeks, but its top fund manager remains cautious about the eurozone's crisis-racked debt markets.

Rick Rieder, BlackRock's chief investment officer for fixed income, fundamental portfolios, said in an interview Wednesday that he has bought short-dated Spanish government bonds since the end of June. He also added to his holdings of Italian government bonds, both short-dated and in the 10-year maturity.