America Online Inc. said vandals had broken into its AOL service.

America Online Inc. said vandals had broken into its AOL service and gained access to an undisclosed number of member accounts, highlighting the vulnerability of even the world's largest Internet services provider to the threat of hacker attacks. The software virus attack appeared to be similar in kind, but by no means in scale, to the ``ILOVEYOU'' virus that temporarily paralyzed tens of millions of computers last month, penetrating networks in government and companies worldwide. ``A small number of member accounts may have been illegally viewed,'' America Online spokesman Rich D'Amato said Friday. ''We are aware of claims that a small number of member accounts were illegally accessed. We take these claims seriously,'' he said. The perpetrators of the attack targeted AOL customer service representatives with e-mails containing a ``Trojan horse'' attachment, that, when opened, created a connection to the sender's computer and allowed access to some AOL accounts. He stressed that the hackers involved did not appear to have gained access to AOL's 23 million-member database of subscribers, or data on users of other services that include CompuServe, Netscape Netcenter, ICQ and other popular sites.