It wasn’t until late Tuesday night that Google responded to Twitter’s comments about the search engine’s announcement that it will start incorporating Google+ information into its search results.

Twitter had spoken out after Google’s announcement about “Your World” earlier that day, saying that showing results from Google’s social network on the main search page was “bad for people, publishers, news organizations and Twitter users.” Results from other sites, such as Twitter and Facebook, do not appear on the Google main search page.

Twitter and Google used to have an agreement that allowed Twitter messages to appear in real-time search, but that contract expired in July. The two companies have been tight-lipped about why that deal fell apart, but Google appears to place the blame on the micro-blogging company in its latest statement.

“We are a bit surprised by Twitter’s comments about Search plus Your World, because they chose not to renew their agreement with us last summer,(, and since then we have observed their rel=nofollow instructions,” wrote a Google representative with access to the company’s Google+ account.

“No follow” instructions, for those who aren’t familiar with the search world, is an instruction that sites put in their code to indicate to search engines not to count links to Web sites toward search engine rankings. In essence, Google was saying that it doesn’t index tweets because Twitter doesn’t want them to be indexed.

In an earlier statement, Google said that it would be willing to work with other social networks to enable their users’ personal information to show up in the personal search results. On his blog, Matt Cutts of Google’s Web spam team explained that open, public content that’s hosted on other sites, such as Flickr, also show up in Your World personal searches.

Still, Google+ content appears to be clearly promoted over other social and sharing sites, as Search Engine Land’s Danny Sullivan has illustrated. His screen shot shows that Google+ results exclusively populate the “suggested People and Pages on Google+,” which provides a huge incentive to brands to rush to the social network and create pages on Google+ rather than on Facebook or Twitter.

Sullivan, who writes exclusively about search engine issues, tracked down Google executive chairman Eric Schmidt on Wednesday at the Consumer Electronics Show to ask him about the new search results. Schmidt said that Google would need to have a “conversation” with sites such as Twitter and Facebook to discuss having their content appear in the search results.

“The core question is, ‘Would we be willing to [include Facebook and Twitter],’” Schmidt told Sullivan, “and the answer is, ‘We’ll be happy to talk to them about it.’”

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