Google Inc., fresh from losing a bid to buy thousands of patents from bankrupt Nortel, lashed out at its biggest rivals on Wednesday, accusing them of banding together to block the Internet giant in the red-hot smartphone arena.

Google Senior Vice President and Chief Legal Officer David Drummond paints a picture of rivals envious of Android's success, noting that more than 550,000 Android devices are activated daily. "Patents were meant to encourage innovation, but lately they are being used as a weapon to stop it," Drummond wrote in a blog post.

BBC News reported that Microsoft fought back saying Google had been invited to bid with it on key patents but turned down the chance. The statement comes after Google lost several battles over patents covering technology used in handsets.

The three rivals - Microsoft, Oracle, and Apple - pecked away at Android, suing Google for violating various patents in creating the popular operating system, Andriod. "But Android's success has yielded something else: a hostile, organized campaign against Android by Microsoft, Oracle, Apple, and other companies, waged through bogus patents," wrote Drummond.

Oracle filed suit a year ago, accusing Google of infringing on patents related to Java, which the database company acquired when it took ownership of Sun Microsystems in early 2010.

"Microsoft and Apple have always been at each other's throats, so when they get into bed together you have to start wondering what's going on," Drummond added. He referred to "a hostile, organized campaign against Android by Microsoft, Oracle, Apple and other companies, waged through bogus patents."

Microsoft and Apple had teamed up to acquire patents previously owned by software maker Novell and bankrupt telecom firm Nortel Networks Corp. to ensure "Google didn't get them," Drummond said.

Google has also spoken about its interest in acquiring InterDigital but could face competition from Apple, Microsoft and many others.