In an attempt to rid its Blogger service from spam blogs, or splogs, Google mistakenly flagged a number of legitimate sites last week, prompting the company to scramble to unlock them.

A bug in Google's data processing code caused the problem, leading the detection system to lock Blogger blogs that had otherwise passed the inspection by the company's spam algorithms, Google said on Saturday in an official blog.

"We are adding additional monitoring and process checks to ensure that bugs of this magnitude are caught before they can affect your data," wrote a Google official named Siobhan in the Blogger Buzz blog Saturday.

Google didn't immediately respond to a request for comment, so the scope of the problem isn't clear, but it apparently was significant, judging by the contriteness expressed in various official postings.

"We want to offer our sincerest apologies to affected bloggers and their readers," the official wrote. "At Blogger, we strongly believe that you own and should control your posts and other data. We understand that you trust us to store and serve your blog, and incidents like this one are a betrayal of that trust."

Google, which sent e-mail to the horrified publishers of the flagged blogs notifying them their sites had been locked after being classified as spam, first acknowledged the problem on Friday afternoon.

"To those folks who have received an e-mail saying that your blog has been classified as spam and can't post right now, we offer our sincere apologies for the trouble," a Google official named Brett wrote on Blogger Buzz on Friday. Google posted a similar announcement on another official Blogger blog called Blogger Status.

All blogs incorrectly flagged as spam have been reinstated, according to Google.

Blogger users began reporting the spam-identification problem early last week to the official Blogger Help Group, starting numerous threads about the issue.

The intensity of many of the complaints highlights the sense of helplessness individuals and businesses feel when a trusted technology provider fails them, even if the affected service is free, as is the case with the Web-hosted Blogger publishing platform.

With the popularity of cloud computing rising, many users, from individual bloggers to large corporations, are increasing their use of Web-hosted software, which offers a number of advantages but leaves them with little power to address outages or loss of data, since vendors have the applications in their servers.

The IDG News Service is a Network World affiliate.