There follows the text of eight e-mail messages and a list of web links of a more or less acrimonious anti-Israeli nature.
The attack, led by self-styled "Doctor Nuker, founder of the Pakistan Hackerz Club", included the publishing of critical emails downloaded from Aipac's own databases, as well as credit card numbers and email addresses of Aipac members.
"The hack is to protest against the attrocities in Palestine by the barbarian Israeli soldiers and their constant support by the US Government," the hackers wrote.
"Instead of writing articles or putting pictures of Israel's atrocities in Palestine, this time I've put e-mails and comments that I got from the web site."
There follows the text of eight e-mail messages and a list of web links of a more or less acrimonious anti-Israeli nature.
In the past year, the Pakistan Hackerz Club (PHC) is reported to have defaced more than 100 internet sites, most of them official Indian sites, to protest on behalf of Kashmir separatism.
Cyberwars
Correspondents say "hacktivism" - as the political hacking is called - is on the rise, as the practice is easy for activists to make a big splash with little risk.
There have been numerous successful and unsuccessful hacking attempts since the beginning of the recent Middle East crisis and website administrators on all sides are reported to have been busy defending their sites against attack from enemy hackers.
The computer security site Attrition.com reported at least four other anti-Israeli hacks on Friday by another group calling itself GForce Pakistan.
Previously hackers have targeted the websites of the Knesset, Israel's Parliament, its foreign ministry and an Israeli internet provider, as well as several sites run by the Hezbollah guerrillas.
Aipac spokesman Kenneth Bricker said the hackers were only able to download credit card numbers and about 3,500 names and web addresses from people who had contacted Aipac's website.
The broader list of the organisation's 55,000 members, which he referred to as "the crown jewels of Aipac," are stored on a separate computer system "that was never compromised".
Mirrored
The New York Times reported that Aipac's site was defaced by the PHC manifesto for less than 15 minutes before the organisation blocked access.
The page soon reappeared on other sites, known as mirrors which monitor and preserve hacked pages.
At the time of writing, the site is still not functioning, and Mr Bricker said the group would not bring it back into service until it had completed a thorough investigation and had taken new protective measures.
Mr Bricker said Aipac was now rethinking its web strategy: "All this is new to us, but we're certainly getting a crash lesson."