By Jonathan Fildes
Technology reporter, BBC News
The site's "auto follow" feature raised privacy concerns
Google has admitted to BBC News that testing of its controversial social network Buzz was insufficient.
The firm has had to make a series of changes to the service after a ferocious backlash from users concerned about intrusions of privacy.
The BBC understands that Buzz was only tested internally and bypassed more extensive trials with external testers - used for many other Google services.
Google said that it was now working "extremely hard" to fix the problems.
"We're very early in this space. This was one of our first big attempts," Todd Jackson, Buzz product manager, told BBC News.
"We've been testing Buzz internally at Google for a while. Of course, getting feedback from 20,000 Googlers isn't quite the same as letting Gmail users play with Buzz in the wild."
Many of the firm's new services are tested by the so-called Google Trusted Tester program, a network of friends and family of Google employees who are given confidential access to products before they launch.
Buzz was not tested by this program.
The firm has now set up a "war room" at Google HQ to bring together engineers and product managers to make decisions about what changes need to be made to Buzz.
"If it becomes clear that people don't think we've done enough, we'll make more changes," said Mr Jackson.
He acknowledged that many of the networks "tens of millions" of users were "rightfully upset" and that the firm was "very, very sorry".
"We know we need to improve things."
Buzz was launched on 9 February. The service, which is integrated with Gmail, allows users to post status updates, share content and read and comment on friends' posts.
One problem that immediately caused concern was Google's decision to automatically give users a ready-made circle of friends based on the people they most frequently e-mailed.
The launch was widely seen as a challenge to Facebook
Unless users changed settings in their profile, this list could automatically be made public, allowing anyone to see who a user corresponded with most frequently.
Mr Jackson told BBC News that the decision to create these automatic lists was borne out of the idea that Google "wanted to provide a great user experience straight out of the box".
But privacy experts immediately pointed out this could cause problems for journalists, businesses or even people having an illicit affair.
Evgeny Morozov, a Belarus-born researcher and blogger who looks at the political implications of the internet, also raised concerns.
"If I were working for the Iranian or the Chinese government, I would immediately dispatch my internet geek squads to check on Google Buzz accounts for political activists and see if they have any connections that were previously unknown to the government," he wrote
As a result of complaints, Google said Buzz would now only suggest people who a user might want to be friends with.
The company has also announced steps to make it easier to disable Buzz altogether and to ensure that people's accounts do not automatically connect with online Picasa photo albums and items that people may store in their Google Reader accounts.
The changes were in part thrashed out at a company-wide meeting on 12 February at Google headquarters.
"We realize that we didn't get things quite right - we're working extremely hard to fix this," said Mr Jackson.
He said that "transparency and control" were "top priorities" and that users would "continue to see improvements".
Other possible changes include a better "preferences menu" that will allow users to better tailor what appears in their inbox, and a more prominent "mute" option to switch the service off.
Another idea, said Mr Jackson, was to create a separate service that was not part of Gmail.
"We think that integration with Gmail was absolutely the right way to go - we wanted to make Buzz easily accessible to people," he said.
"We also want to give people who don't use Gmail the ability to use Buzz, so we're exploring the idea of offering a separate destination site."
The most recently announced changes would go live "this week", he added.
"We worked around the clock to make the code changes for these improvements; now we're putting them through a full testing process to identify any bugs and translating them into 53 languages so they reach all Gmail users."
Asked if the Google founders - Larry Page and Sergey Brin - or any of the executive team would issue an apology for breaching their user's trust, a Google spokesperson said: "Google has apologised - we're very sorry for the concern we caused."